I prefer 16:10. If a game doesn’t support it and just displays at 16:9 I just don’t care about the bezels, simple as that. The amount of space you lose is very small compared to displaying old stuff like 4:3 aspect ratio on a 16:9 display.
Honestly from my experience the only thing about proton you need to know is how to switch versions, add launch arguments and how to find tweaks you need to apply for your game to work properly (you can find that out on protondb)
Sometimes you might need to install a custom version of proton called ProtonGE, which has some additional tweaks that some games need to work, so you could learn how to do that too but most games usually don’t need it, so you can figure that out once you encounter such game.
You don’t need to know much about Linux when using the steam deck. There may be some times that you might need to open up a terminal to set something up like cryo utilities and steam deck plugins but you can just follow a guide, you don’t need to understand what the commands do.
To me it definitely helped with stutters in No Man’s Sky, but besides that I’m not quite sure what effect it has.
The only major thing I would personally want is a bit more RAM. 24GB maybe. Some games need both lots of VRAM and lots of normal RAM. This is especially important when you set UMA bufer size to 4GB.
It’s not that important for me though. Not going to be a deal breaker even if they stick to 16.
Probably not. The main benefit for the steam deck is that it is very portable. For this you sacrifice upgradeability and connectivity. The steam deck only has one usb-c port. Yeah you can expand your ports using a dock but it still isn’t as good as having a desktop computer.
If you don’t plan on making use of the portability that the steam deck provides then there probably aren’t many benefits for getting it compared to just getting a desktop pc or a laptop.