1. Depends on how much crap you're willing to put up with. It'll all be worth it in the end! (Pro tip: disable secure boot in BIOS)

2. I wrote a whole guide on the two options, but then accidentally deleted my comment. You can either install Linux on another drive, or shrink your NTFS partition and install Linux alongside it. You can always access NTFS from Linux, but not the other way around (by default). If you don't understand what I'm talking about, you should really look it all up. I would personally just backup and wipe, you can always reinstall Windows if you want to.

3. Have you heard of Valve's Steam Deck? It's a handheld gaming device that can play nearly every PC game, and it runs Linux! Valve made gaming on Linux an absolute breeze thanks to Proton. There are some popular games that don't work, either because Tim Sweeney hates Linux (yes, really) or because the anti-cheat won't accept Linux, but I only know about Destiny 2 and Rust that have that problem. Easy Anticheat works just fine, I play Apex Legends and Deep Rock Galactic with no issues!

4. If you have AMD, you don't even have to think about it. Their drivers are part of the Linux kernel. Nvidia is not impossible to use, but you might have some issues. I experience random desktop environment crashes that I can only attribute to their drivers, but it only happens on startup sometimes, which is the least annoying it could be. If you choose a distro that doesn't mind automatically installing non-free software, you probably won't need to think about it either. The open source driver, Nouveau, works fine but performs awfully in games (or at least it did a year ago).

If you just want some clear instructions: backup your files, wipe your disk and install Linux Mint Cinnamon Edition. It's easy peasy to use and getting the proprietary graphics drivers is only a few clicks away. Just configure your Steam games to run through Proton and you might not even tell the difference.