I realised like a year ago that I get up better if I set an alarm for a 7 hour sleep. I usually wake up before the alarm somehow and if I manage to get up, I won't feel tired the entire day. Did that for a year, then I just forgot and for an entire month I was irritated why my sleep sucked so bad...
First, which game are you talking about? Does it need proton on linux, or does it run natively?
Definitely first install the game through steam on linux and then overwrite stuff.
You should be able to access your windows drive through linux. I would expect it to show up in your file manager automatically and ask for your linux root password when you try to access it.