I am unfamiliar with refind, but from my experience with systemd & grub dual boot, if you do not change your boot order in bios, there is a high chance that the windows boot manager will brick your Linux one, even across drives. My advice for dual booting is to ditch the convenience of using one boot manager. But once again, this may not be an issue you have.
For gaming you should keep in mind that you want a distro with decently new packages to avoid issues with Nvidia & also to have the correct drivers for some titles: fedora is good for a strong base, although I heard they are doing away with there x86 libraries… I prefer endeavor os, but you will at very least need to learn to use pacman and yay, but they aren’t hard to understand if you have basic programming experience. You should also know that almost all games that are not supported on Linux nowadays are either really new, like launch day new, or they rely on an invasive anti cheat: are we anti cheat yet & proton db should give you a decent idea if your library is compatible.
I don’t have nearly enough experience with your second point, my only thoughts are that you should be looking into libre office - it’s the most mature in my eyes, and open office has made a lot of questionable decisions recently. Also as a general rule, I would say there is about an equivalent amount of compatibility between the oss alternatives and the different versions of the Ms office suite, it will be noticeable, but so long as you don’t live and die by formatting, it will just be mildly inconvenient.
I believe you are looking for proton, they are the oss answer to the Ms and Google suites, I don’t know if you will have quite the amount of compatibility you want between people, but if that’s important just use the web versions of your preferred suite.
Vs code is almost entirely open source, as such, there is a project called vs codium which takes the publicly available vs code source code and keeps it fully open source, if you like the visual studio program you will hardly notice a difference.