KDE is not a just-wurks DE just because it looks polished graphically. That's partly because it has a continuous problem with developers enforcing muh vision shit onto it by forcing fancy new features in/removing ones they don't care for without any concern about how it will affect the larger product. Dolphin is still niggers, Konqueror should have remained the default.
Depends on the game but if you go check winehq or protondb for a specific game you can get a decent idea if it will work or not. It's certainly not the case that all
games listing Win8/10 will fail particularly since there are so few engines in use nowadays that often a lack of native Linux support is a lazy faggot dev not clicking a few buttons and getting those few engines to function with Wine/Proton is a solved problem. Almost all games with intrusive anti-cheat will fail by design though.
More generally if you want to go pure Linux there'll be some games/mods, new and old, that simply will not work/will work but without some specific features like multiplayer no matter how much you fuck with them and from there your options are dual booting (not a good idea), running a separate machine purely for windows vidya (inconvenient), just skipping those games or setting up GPU passthrough with a VM (will take a day or two and need a second GPU and some other minor hardware, once it's up and running pretty simple). Once you know what you're doing it's not that common to run into such games though.
If you aren't a retard with a low attention span and can troubleshoot games you'll learn Linux simply by inhabiting it on a daily basis. Pick a decently slick distro and use it every single day without fail then just literally google it easier with a well-known distro
or ask in a thread like this if you hit something you can't yet do.
>you would rather it just be in your repositories,
The problem with Arch is that almost everything beyond the core packages is in the AUR and that has little-no quality control meaning you can easily get broken/misconfigured/poorly placed software. On paper that's a security risk too unless you manually audit the pkgbuild technically for every update too
and most fags will just do it blindly but there have only been a tiny handful of known cases of intentionally malicious scripts. Really nobody should be recommending Arch/Manjaro to new users without a giant warning not to rely on the AUR until they know what they're doing, but then the same new users will eventually stumble onto the need for PPAs or the like for Debian-based distros and those have most of the same concerns really.