You should have some understanding of the nix language to use it, but I wouldn’t worry too too much.
I would also start by installing nix and home-manager on top of whatever distro you already use. For some config, you need to specify things in nix, but for things in home-manager, for example, you can usually either use nix or point to a toml or conf or whatever file.
By vertical tabs do you mean tabs on the side instead of the top? If so, check out the tree-style tabs extension, it’s great.