I think that the sounds make the game what it is, but some of them are way louder than the others, and cover up footsteps, there should be an option to disable all but footsteps and weapons, without having to mute it all. As for ogg vorbis, I love .ogg, do it! In my experiences, .ogg at the same bitrate as .mp3 for ripping CDs, .ogg always comes out better on my headphones, even though they sound the same on my crummy real speakers, and the .ogg files are always smaller then the mp3's too.
Also I'd like to request the quake 3 "killing spree" sounds and all that be used, almost every game I play there are servers running mods that use the quake 3 sounds, because they rock.
As long as none of those horrible wanna be rappers on the forums make sound files, I'm down.