I can answer some of these from experience.
Performance is a wide metric, and it really depends. It will use less resources due to less software bloat, and scales better on older hardware, but thats not applicable here. AMD does better because its software is integrated better, but I’ve used nvidia just fine on linux in the past year or so without too much hassle. Some video games do run better, but case by case basis, and there doesn’t seem to be consistency. I’ve found some games running better with steam proton vs native as an example.
The current version of mint should be fine with cinnamon. I haven’t tried edge, which uses the latest kernel, but it should also be fine with your hardware setup.
I’ve attempted to use VR with little success on my end. I have a CV1 oculus rift, and wasn’t too happy with how much additional work was necessary. Maybe the index has better implementation, but I can’t say for certain.
You just download steam, and download the games via steam. Inside the game options, you enable compatiblity and and either the latest version of proton, or proton experimental. You can use protondb.com to see what games require what. For a vast majority of games, steam experimental works just fine. There are some edge cases where GE Proton was necessary, or maybe some launch command options needed to be addressed, but overall the experience of playing a game is extremely smooth now.
I dual booted with linux mint. It ran just fine switching between partitions, and it also gives you time to experiment and test drive without committing to it.
I can also recommend Nobara as well, since your friend uses fedora. Its a fedora spin that has gaming done for you out of the box, but these things can be replicated with a bit of effort.
LFS