1) How do you build log bridge?

2) Is there a manual somewhere ?

3) Is there a list of commands and shortscuts?

4) How exactly do you win a level?

1.
https://crafttheworld.gamepedia.com/Log_Bridge

2-3.
IDK about an official manual, but there are lots of guides online.

4.
You need to find a portal underground and repair it by collecting items from bosses/guardians, that are also hidden in underground chambers. Equip your dwarves well, for they are though.

It's been a while since I last played, but if you have questions, I'll try to help :)

I started to play this game, but it's not at all clear what needs to be done.
The tutorial at the beginning is very bland and explains almost nothing, the items bar is really limited and I always have to replace objects, also how to build a house with walls etc.?
Why do my dwarves keep sleeping instead of working?
Why are they always incapable and never able to execute orders well?
I thank everyone who can help me out.

To build a house you need to first build the "back-wall" of the house, and then you can build the walls on the sides. To build a wall, you need to build another wall-block on the top of the already existing back-wall.

IIRC dwarves sleep when their health is below max.

When giving orders make sure they have a proper path leading there. Make ladders and scaffoldings, they are easy to make, and provde good pathways to high places. Also, you can instantly place and remove scaffoldings with a click.

I forgot: A house only counts as a house if it is both closed from all sides, and have a totem inside. Totems have a limited range, which will limit the size of your house. Later on you will get more totems, so you gan expand.

On later levels I recommend building underground shelters instead of houses for... security reasons.

If you build underground, you wont need the back wall either. Your shelter needs to be closed on four sides, doors and hatches count (obviously to get in and out.) If its a "house" above ground, you will need the 5th, back wall. Red/Orange stars will appear to guide you on where there is a "hole" in the shelter. Defensively speaking, build underground. Its much, much easier for a new player to learn.

Beds are needed within the shelter (as mentioned, where you place the totem within the four walls) to maximize sleep. The greater your comfort level, the quicker they will recover.

Food - You will need to build and place a table, then place food on the table. Find the food in your craft menu, drag them to the quick bar, then click and place the food on the table. As you start, basics foods dont need to be cooked, like pine cones, but they will tire of them quickly. More food varieties allow greater time between meals and they will work harder/faster. Some foods have specific benefits, read the descriptions in game.

Follow the quests as they pop. Yes, they are simple and dont explain a lot but they force you along the tech path so you get familiar with it.

Finally, the only real thing to fear is the every 48 minute or so monster invasion. Build a few simple walls (you can literally just pile some stone or dirt), dig some ditches, anything to slow them a bit. Early on, dont bother trying to fight them until you at least have some decent weapons. Armor is debatable based on the monsters they send.

I forgot i had posted this https://www.gog.com/forum/craft_the_world/new_player_tips

Based on an older version but still holds true. generally...

Thanks again to all for the suggestions, I have also read the guide of muttly13 but I still have some doubts:

1) How I can build the "advanced" walls? I mean the one thin that I can see in some screenshots of the game.
2) I have the farm but I have no idea on how to capture the animals, my dwarfs kill them everytime.
3) How in the hell I can turn the direction of objects? Doors and turrets for example.
4) I have more than 20 hours in the game and I'm still at the first level, it's normal?
5) I have nearly consumed all the iron in the world, there is something I can do to find more?

Thanks!

1 - If i am understanding correctly, you mean things like Ice walls, wood, etc? Those need to be crafted first and then placed like other objects.

2 - You must first craft and place a trap. A sheep or bird will cross over it and spring the trap. You then have the option of "catch" if you have a 5 fence farm ready. Once you have them captured, If you right click them you have the option of "cut" for sheep (and sheep clones). Birds require no interaction, they will simply drop feathers and eggs.

3 - For place-able items, if you select the item from your bar as though you are going to place it, clicking on an existing item will flip its direction. For example, place a door. Wait until its placed, then select the door from your bar again and place it over the existing one. It will flop direction. Turrets will do so automatically as needed.

4 - Depends on what you mean. If you mean Dwarf level, as in you have but 1 dwarf, thats horrendous. but I imagine you mean you are still on the forest world, thats fine. You can stay as long as you like, you just need to find the five portal guardians and their scrolls. Just keep digging and you will come across them if you havent. As a level set, i think the first time I played I was on the forest world for 30 hours. Today my best time has been about 14 hours. You can race to the end of course and get much better if thats your thing.

5 - Barring some kind of crazy bug, there is plenty of metal on each world to pretty much do what you want. Conceivably there isnt enough mythril to deck everyone out, but it shouldnt matter. One thing to note, you can scrap old items in the craft screen. Simply drag the item out of your inventory onto the little "craft" box and it will shift colors to show you that you are "scraping" and you will get back many of the base materials. For example, scraping your stone axes will result in a stone and a log (usually) and so forth. You can do this to most items, the only ones you cannot are the ones that are created in stacks, wall tiles for example.

Oh, and one other thing that you havent asked about but made my life easier as I learned... Feel free to spend your money. There is no "super happy fun" item at the end you need to save for. Personally i buy books as I need them and a couple dragon eggs as I am too lazy to harvest them. they have also added a few cool mana based items that are worth saving for if you burn your mana quick or dont like to build multiple stock piles. The game is still perfectly playable without purchasing anything, just makes your life easier in spots.

Thank you very much for the tips, especially for the scraping, I didn't know it was possible.
And now my farms are useful! XD

Now I have consumed entirely the first world and I have all the pieces for the final portal!

Before completing the level, however, I wanted to dedicate myself to the last achievements left at this stage. Unfortunately I have problems with the achievements "Manufacturer" and "The worst that could happen", someone has some advice? Because I think they can be bugged.

There are guides all over, this one has descriptions and such. If it doesn't have what you need, you can google specifics and get some good data.

https://steamcommunity.com/sharedfiles/filedetails/?id=394288622