Sorry for not addressing any of your points directly, but i was in a similar spot at the beginning of the pandemic.
The way i did it in the beginning was punch a ~40GB hole in my windows 10 partition, installed arch into it and set my system up for dual boot with help of archwikis excellent documentation and grub. Then i gradually tested many of my applications and games and found out most of it worked out of the box. For games, even if not using steam for valves excellent proton support, looking into lutris worked wonders (amd gpu thogh). When i found myself booting up windows less and less, i shrank the windows partition to a minimum and expanded the arch partition. this obviously doesn't apply if you have ample diskspace or multiple drives.
regarding the AUR: i started without a AUR-helper and installed AUR packages the way it's recommended in the archwiki. it's very manual and a little tedious, but you learn a lot about the arch build system and the way it uses PKGBUILD-files (basically shell script) to prepare and install packages. Even with an AUR-helper, it's still your responsibility to check these files for malicious content.
Can't help you with virtualization though, other than anecdotes on the difference between GPU-passthrough and simply dual booting windows not being that great.