DLC

To get all the official DLC, go here
Download those that are not included, install them all and don't worry no more.

Promotional DLC Giveaway

Follow the link to get the following DLC registered to bioware account absolutely free of charge:

Dragon Age: Origins
- Memory Band
- Feral Wolf Charm
- Guildmaster's Belt
- Band of Fire
- Dalish Promise Ring
- Bulwark of the True King
- The Edge
- Embri's Many Pockets
- Bregan's Bow
- Helm of the Deep
- The Lucky Stone
- The Lion's Paw
- Pearl of the Anointed
- Mark of Vigilance
- Amulet of the War Mage
- The Wicked Oath

Dragon Age: Origins - Awakening
- Bulwark of the True King
- Bregan's Bow
- Pearl of the Anointed

Note: The DLC in question are the various weapons and items players got as pre-order bonuses when the games were first released.

Getting the stuff is as simple as logging into BioWare's site, selecting your platform and which game, and pressing a button. You'll be able to download your new toys soon afterward.

Instalation

1. Download the DAZIP file.
2. Locate daupdater.exe in your game folder. For example: C:\Program Files (x86)\Dragon Age Origins\bin_ship\.
3. Run daupdater.exe
4. Click Load DAZIPs and browse to the location where you downloaded your DLC .dazip file.
5. Install it.
6. Run Dragon Age: Origins and check your DLC

Note: You might want to change the *.zip into *.dazip if you find daupdater can't see the zip files.

Troubleshooting

To activate these DLC don't forget to:

1. Go to official Bioware website
2. Login with your Origin account or create a New one.
3. Register your Game as well as Ultimate Edition DLC Key.
4. After that login in the game with the same account and you good to move to MODS :)

MODS

Tools - Perfect Mix - Graphics & Atmosphere - Gameplay - Bonus

Note: Instructions and download link can be found in respective page.

Tools - utilities that you need to install the mods:

- DAO - Modmanager 1.9d - Use it to install all the mods.
- CharGenMorph Compiler 1.2.3 - Searching through all override directories and reconstructing a singular "master" xml file containing all the values. It makes multiple models mods work together.

Perfect Mix - some that I find essential:

- Lock Bash 7 - Bash open locked chests and doors. The way the game should have been.
- Character Respecialization 1.6 - Allows the player to reset the attribute, specialization, spell, talent and skill points of any party members.
- Beyond Ferelden Base Chest 1.0 - Nice storage chest in the camp.
- Madd Gift Guide 1.1 - Adds (Intended Companion) Text to the front of a gift item description. Also lets you know if an item is plot related.
- No Helmet Hack 1.6 - Hides helmet.
- White Teeth 1.1 - Changes the rotten yellowish teeth of all characters to a white color.
- Pineappletree's Vibrant Colors 1.31 - This adds 48 new hair & eyebrow colors, 40 new skin tones and 30 new eye colors to the Character Creator and replaces the 11 eye colors.
- More Hairstyles 0.51 - Adds new hairstyles available at character creation.
- Natural Bodies all in one 3.0 - Naughty stuff... Totally PG 18+
- Better "huehue time" Cutscenes Zesty 2.0 - Goes well with Natural Bodies pack. Again, PG 18+
- Theta HD 1.2 - Enhance Dragon Age's worst textures, and to fix graphical inconsistencies, without hurting performance or consuming excess RAM.

Note: To put together Pineappletree's Vibrant Colors and More Hairstyles use CharGenMorph Compiler

Graphics & Atmosphere - enhance graphics and ambient even more:

- Improved Atmosphere 2.0 - Improves ambient NPC behavior, gives most NPC's different clothes or equipment (to make the world seem bigger and more varied), adds many new tints for armors and weapons, restores cut content, fixes bugs, and much more.
- JB3textures 3.1 - Much better and sharpen textures.
- Dragon Age Redesigned 7.3c - Redesigns the WHOLE of the NPCs in Dragon Age to fix skin issues, face proportions, personality mismatches, gender identification, race identification, etc. to better fit the lore of Dragon Age.
- Dragon Age Graphics Enhancement 1.0 - A graphics injector that adds sharpening, saturation, anti-aliasing, bloom and removes the red tint from the game.

Note: I don't really like this 4 because I like vanilla textures more and Atmosphere & Redesign changes too much of the game making it too different from original. It really improves the game, but I guess, I'm just old fashioned. :D

Gameplay - enhance gameplay with full new features:

- Extra Dog Slot 1.41 - Allows you to make your pet mabari war dog a permanent 5th travelling companion.
- Advanced Tactics 3.1 - This add-in fix various bugs in tactics system, party members behaviors and AI. It enable new conditions and actions in the tactics system that give you the opportunity to configure your followers more precisely.
- Even More Advanced Tactics 1.0.0 - Introduces improvements to Tactics system. New Conditions, new Target Types, new Commands and completely new features are added.

Compatibility: You have to choose between "Advanced Tactics" and "Even More Advanced Tactics". First one is more stable but second one has more improvements.

Note: But it affects the core gameplay as well as the stability making it, at times, too easy.

Quests & Companions - some new addons to keep you busy:

- Ser Gilmore companion NPC - Fully Voiced 3.1.1 - Brings Ser Gilmore back into the game as a party member to accompany you throughout the game. It contains a romance, friendship and open relationship paths for all male and females from any race and origin.
- Ser Gilmore and dog companions in Awakening - Fully Voiced 1.1 - Ser Gilmore and your dog will join your party and accompany you through Awakening.

Quests: There are so many good quests out there that I couldn't decide which to add, so I give you the links and it's up to you to choose what adventure to follow. :D

- Quests
- Dungeons

Bonus - some miscellaneous mods worth a look:

- Morrigan Restoration Patch Dialog Fixpack 1.1.0 - This restores several missing and fully voiced scenes to the game relating to Morrigan in addition to fixing innumerable issues with various parts of her dialogue not triggering correctly. Note: Doesn't work with Russian Localization (didn't tested other languages).
- DahliaLynn's Sleep Until Dawn 2.2 - Click on your camp tent go to sleep alone, with dog, or snuggle with a love interest. Wake up to a beautiful morning in camp ^_^
- HAIRSTYLE DAY 1.7 - New hairstyles for the character creator.

Note: These mods are a little something extra for your pleasure.

ADVICE:

If you are playing this game for the 1st time it's a good idea to limit yourself to Perfect Mix - it's just little tweaking and it doesn't change the core game, only prefects it. And then, on a 2nd playthrough, install Graphics & Atmosphere + Gameplay - since they change the game much more and alter your experience as well as overall feel.
Also, it's better to install Quests & Companions on your 2nd playthrough, so that you can see new things!

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Notes on MODS

I've manage to install every single one of the mods in here and made them work together, so all of you can. The only problems I've found is that:

1. Not all of them are compatible with Russian Localization (didn't tested other languages) and substitute some dialogs by english.
2. Dragon Age Graphics Enhancement 1.0 is heavy and may cause FPS drop on slower PC's.

This guide was initially written for myself, cause I'm dumb and I'm totally going to forget everything. But then I decided to write it properly and publish to steam for everyone to enjoy. And now it came time to port it over to GOG.com cause I OMG OMG OMG LOOOVE GOG :)

And so, I think I won't further improve this guide by myself because I'm quite happy with it's current state. But if you have any suggestions please write in the comments and I will try to include them.

Thank you for reading, I hope it was useful.

Just a note, all that DLC is included. The only DLC NOT included is the Bioware Made Camp Storage, and the Collector's Edition DLC.

So no need to download all the other just get

CE items
Bergen's Honor
Grimoire of the Frozen Wastes
Final Reason

and maybe the bioware made camp chest.

Also take the mod recommendations with a grain of salt as they are just one person's opinion. Pretty much any fixpack is a must-have, and OP mentions almost none of them. And nude mods and better sex scenes are hardly "essential." Conversely, I find Improved Atmosphere and Dragon Age Redesigned are far more worthwhile.

I would also suggest getting the Sacred Ashes mod for Morrigan and Leliana. Way better looking than the original models.

Can you post the process for manually installing mods and include the information that would cover adding loose files to the override folder.

Exactly :)
Nude mods and better sex scenes lines were hidden on steam, I haven't thought it through here :D But meh, that works just fine anyway. Whatever grinds your gears, my gears are grind when I have a payoff in form of proper sex cut-scene and for that, I need natural bodies mod, otherwise they just look silly :)

I haven't tested any fixpack, since I don't play in english, and they don't work with other languages, but if you can write them down, I will gladly add them to the guide :D Not really, it's been a long time since I played the game, and I don't remember that much, but it's not that hard, way easier than morrowind or oblivion process.
You see all mods have installation guides on the nexus page and some FAQ on compatibility, so if I managed to install, I'm sure you can do it with much ease. Hope that helps :)

Stay safe on field of Ferelden!

From the changelog of the newest patch:

Bonus campaign and DLC patch (19 July 2016)
added missing DLCs : Collector's Edition Items and A Tale of Orzammar bonus campaign
includes previous hotfix and can be installed on gog-3 & gog-4
warning: patch overwrites any existing AddIns.xml file, if you have any additional bonus content installed you might want to backup this file!

So what is still missing? The camp chest and pre-order stuff?

Nothing is missing. The first post of this thread is largely pointless. All the DLC is automatically present after you install/patch and start a game. You don't need to do anything.

The General Camp Chest is a third party mod, not DLC.

There is a storage chest in Wardens keep, since Wardens keep is included you would have access to that chest.

You also don't need any mods to play. Many mods will also cause their own problems and possibly conflict, or lower your framerate on less powerful computers.

Thanks for the info.
I know about using mods with this game.
I wondered if they fixed the ancient elven boots not spawning...

I have a problem with ".override" mods, I am unable to install correctly them with "DAO-Modmanager". I can install them, but the "Config"-command in the override-mod is greyed out. I was able to install and configure ".override" mods in Windows 7 64 bit, and I used the original disc-version of the game, not the GOG-version. I currently have Windows 10 64 bit. Does anyone else have this problem? The override mod I am trying to install is "Natural Bodies all in one", if it makes any difference. :-)

I am on Windows 10 and can use/config that particular mod. Check your UAC settings.

I executed DAO-Modmanager with Administrator-rights and it did the trick. I feel so stupid now... :-D
Thanks for your help. :-)

For people reading this in the future, this is no longer true. 4 days after LordRikerQ said this, GOG released an update, which you can see in the changelog. Changelog text: "added missing DLCs : Collector's Edition Items and A Tale of Orzammar bonus campaign"

So the GOG version is 100% complete.

Okay, sorry if this should be obvious, but I've poked around some of the different DLC topics on the GOG forum here and I'm still not totally clear-- if I buy and install the game through GOG, will it just have all the DLC and the expansion installed and ready to go, with no additional installations or redeeming codes and signing into an EA account required?

I own the game on console and Origin, and honestly I would be willing to buy it a third time on GOG at the current sale price just to avoid any DLC hassle. Last time I played the game on Origin, getting all the DLC up and running was kind of a pain.

Any clarification is appreciated.