You can just keep your old system, no need to switch everything at once.
Or just put all your data on a external drive to make sure.
Most games work....the few anti cheat ones wont be missed for that anti cheat is basically a trojan and hence not ethical software.
You dont need the terminal...but as a protogen u should come natural to you to use it if u need :P
If u can js already then dont fear bash its way more easy than js, u can do it and looking stuff up sometimes is is also fully normal. In fact that makes linux kinda neat instead of fighting menues and trying to find the right setting for a thing...google usualy just spits out a oneliner u can just drop in the terminal and your problem is solved :D