Definitely you can use mods, but some of them can only be used in certain servers, specially my favorite one, the 3rd person cam :(
Don't know if online is still alive, i don't play it for a few months from lack of time and other games, but you could always find a game.
And playing with keyboard and mouse if you want is a big plus for me :)
Flow -"The important is to pwn other ppl"