Ok, before I jump into the "end game" (finish the Artemis story), I have a question...

There are still quite a number of unfinished other quests left. For example I still need a second Vy'Keen dagger to give to the weapons specialist (I can't seem to find one anywhere!), and also I haven't finished the Atlas path yet. There are a few smaller tasks such as I promised to take a picture of a desert world but can't seem to find one of those either, plus I was tasked with building a marine base which I haven't done yet. Oh and the base computer is still sending me to other worlds to find archive fragments.

Will I lose all those when I finish the main story line, or will I still be able to finish the other tasks afterwards?

You will be able to finish them. I recommend creating a backup of your save game folder. In fact, I strongly recommend doing that. Very. Strongly. :)

Vy'Keen daggers can be bought at planetary Trading Outposts in Vy'Keen systems.

The base computer will continue to send you around, but you can choose to ignore it, if you have all the base parts you need.

To add to what ksj8ak2 said: you can buy the daggers from any pilot that lands at the trading posts on Vy'keen planets.

Desert worlds are any that have Cactus Flesh as a resource. They don't actually have to be called 'desert'in their description.

Weapons specialist: When I don't feel fit for battle, I sometimes build a small wooden fort and take them out from within. Boring, but what can you do... Careful, though, in the heat of battle they may forget the rules and walk through solid walls o_O. But I don't think there's a way of sneaking through this quest line.

A method I found for this :
Have your Starship nearby. Run around on foot and take out the floaty sentinels, and the armoured variety, and the dog types, then run around in the same vicinity until the big guy shows up. Then jump in your starship, take off but be sure not to fly away too far - If the search clock resets you have gone too far - Take out the big guy with your starship weapons just by keeping looping around and quickly targeting the armoured pieces and finally the head. Then fly just a little bit away and the Sentinels clock count down searching for you should kick in, start circling the area so that you do not leave the area and the search clock counts down to zero.
If you have taken out one round of all sentinel types, and then run down the search clock to zero, the sentinels will bug out, land and go talk to the armorer :)

Tips :

While running around on foot, strafe. With keyboard and mouse use A and D to keep changing direction running sideways, and keeping the target in sights with the mouse. They are not as good getting a bead on you strafing as you are shooting them running round in circles .. If you use a controller you will need to learn how to strafe and target simultaneously with whatever button / stick combination you need to do that.

Getting in the ship to take out the big guy is not necessary, you can kill them by strafing, anticipating that horrible scatter attack they have and using jumps to escape it. The thing is if you are in your ship when the big guy goes down, the next round of sentinels cant find you so easy up in the air, so the countdown searching starts and you flying around in circles keeps them from finding you.

Dont fly too high though, otherwise Sentinel Starships and Freighters join the battle. Just high enough to keep from hitting the ground or getting too close to the ground sentinels again, and close enough so that the timer keeps counting down.

Oh and having max adjacent upgrades for shields / lifesupport / multi-tool upgrades etc helps greatly too :)

https://www.reddit.com/r/NoMansSkyTheGame/comments/99e14k/visual_guide_the_technology_configuration_chart/

(Right click the image there and download it so you can magnify the image in something like Windows picture viewer)

You can have your one buildable upgrade for anything which you learn from a blueprint, plus 3 adjacent S Class upgrades, plus 3 adjacent upgrades in the Tech slots aswell. So Jetpack + Blueprint Neural Stimullator + 3 times adjacent S Class upgrades to Jetpack in the Main inventory, plus Blueprint Rocket boots + 3 times adjacent S Class upgrades to the Jetpack in the tech slots = Max upgrades to the Jetpack. Sometimes you only get one Blueprint upgrade like for shields, us it with 3 S class adjacents in the main inventory and then 3 additional SClass in the tech slots - Of course expanding all inventory slots to their max needs to be done first to allow for so many upgrades to everything you need, thats why the armorer ask if you are ready :)

Latest Beyond update now allows us to move everything around in inventories, including the basic stuff like Jetpack, so you can achieve maximum upgrade adjacency bonuses for everything.

I still have a few things to get (pulse drive on my starship for example could do with 3 S Class upgrades in its Tech slots), and there are some adjacency differences in Beyond that the link I gave above does not cover, but here's my setup so far since I started a new game with Beyond (No cheats, no save game editor, no mods) :

Screenshot 1 - https://i.imgur.com/sB2v07y.png
Screenshot 2 - https://i.imgur.com/tow2kHq.png
Screenshot 3 - https://i.imgur.com/tR7l3yA.png
Screenshot 4 - https://i.imgur.com/uNvjA6T.png
Screenshot 5 - https://i.imgur.com/GUNFnFS.png

Artemis done, now following the Atlas Path, most base building quests done with a few to-do like Exxocrafts, working towards an S Class Freighter (Currently have an A Class) and then to build that up.

Edit : Oh and something else which is new to Beyond - Hyperdrive upgrades - It used to be that if you had the Indium drive installed on your starship, you did not need Cadmium and Emeril drives, because Indium allowed you to go to all colour systems. New to Beyond though is if you have all 3 installed, you get better adjacency bonus for maximum Hyperdrive Distance. Play around with placing them adjacent and you will find one configuration makes you go further than any other configuration.

You don't have to break down the tech before you make the switch. You can break down broken tech as well and still get the same mats back.

Wow, thanks so much for all the detailed information and additional tips!

I too haven't used any mods (yet) and I will definitely never use cheats or save edits. So it might be a while before I gather those upgrades ^_^ But once I am ready, I'll revisit my old base and finish that mission... hopefully soon.

Meanwhile I landed on a nice prairie-ish planet in Eissentam after I re-selected Green (sorry, TerriblePurpose, I saw your post after I had already gone back to the saved game). Funny enough this time it was called "Serene" instead of "Inspiring", but eh, it's both good.

Might set up a base on that planet and go exploring Eissentam for a while - then revisit the old mission and finish those sentinels once and for all :)

I got a new freighter! I went on a rescue mission and saved this gorgeous beast from nasty pirates. The captain offered it to me at a discount and now I'm broke, haha.

Meet Gathering Storm (yes, Expanse reference here) - A class with 34-4 slots... I love it!

https://imgur.com/HCVCaau

Yeah I struggled with the "kill 8 sentinels" mission too. What helped was having the javelin and the shield. Using the javelin works well with all the small guys and the quad. Save the shield for the big mech...raise the shield and wait for the mech to fire then blast away at the 5 armor points (the game doesn't explain this well but the mech has 1 armor point on the body and two on each leg). Once the armor is gone it basically fires bolts constantly so just strafe and fire with javelin or boltcaster.

Or use the plasma grenades if you have them - just make sure you are far enough away.

Many things can be produced very easily using the 2 and 3 slot refiners.
Chromatic metal is one of these. You just need some of the metal you get on red, green or blue stars to start the process.
Carbon is another using condensed carbon and making carbon crystals, though this is slower and you probably want several refiners working at once to make it fast enough.

Not sure why turning A to B and then back into A yields more of the original product, but that's how it is.

Some things cant be made easily, ie oxygen.

Thanks :) In fact now that I have a freighter with all the missions, money comes easy... as you guys promised :)

In other news: VICTORY! I finally finished the 8 sentinel quest. But... in all truth... I think it was a bit of a fluke (not to use the word cheat, haha). Following some of your suggestions, I built a wooden shed for hiding. I didn't add a roof, which apparently isn't seen as going indoors.

So from that shed I killed the first 2, then 2 more... then prepared for the "robot dog" which I've never been able to survive. I was standing there waiting, then it said "sentinels searching... searching... searching.... deactivated."

Funny enough the count still remained at 4, but no more sentinels were arriving. It just so happens my base is not too far from a depot (walking distance), so I ran over there and killed 4 more (this time out in the open), then started running back to my base before enforments could arrive (they did try to catch me, but apparently our traveler can outrun them easily).

So I killed my 8 sentinels without ever encountering the scary stuff and I was offered a crappy multi-tool in reward, which I declined.

FINALLY I can proceed with the next stage - which is moving those "experts" to my freighter. Question: can I just delete their terminals on my old base and rebuild them on the freighter without losing their progress/missions?

Yes. You can delete the station and the specialist disappears along with it. They'll reappear whenever and wherever you rebuild that station.

ISTR that during at least one of the releases (and perhaps now) the specialist didn't immediately pop into (re-)existance but only put in an appearance after the player returned to the base (after a save / reload?).

They don't seem at all put out by their enforced absense. Perhaps they return to their original space station to swap stories about "You won't believe what that Traveler I work for has been up to!"

I don't know for the 2.14 version of NMS, but if you move your specialists into your freighter to do the base quests, get prepared that some quests will have broken waypoints blocking your progress, you better do these quests on a terrestrial base. If you do it on the freighter, make a backup of your savegames just in case.
AFAIK, the Farmer is the only one which is ok to do on the freighter.

Thanks, I'll finish their missions before I dismantle their terminals and move them to the freighter.

Meanwhile, another breakthrough: my latest proud possession: https://imgur.com/YWuB4CW

Yep, I now have upgraded to an S class multi tool, yay! After about 60 jumps, I could buy it at a space station. You can imagine I jumped on it!