For #1, I've made the realization that most distros are lightweight skins or addons on top of another distro. Most of the time, if you start with the base distro, all you have to do is install some apps, change some configurations, and suddenly you have that other distro. It is much easier than doing a reinstallation.
If you filter out all of these distros that only do a little on top of an existing, you're left with a quite small number actually. I'd bet it's less than 10 that are not super niche. Fedora, Arch, debian, gentoo, nixos are the big ones. There's some niche ones, like void Linux and Alpine.
So I'd say if you try all of those, you don't need to try any more ๐
For #2,
For gaming, if you use steam, you may not face more than the following:
For programming, you will love your life because everything programming is way easier on Linux.