#3
Rammstein - we three kings
Nightwish - silent night (might work pretty well)
Muse - Merry Xmas Everybody ( i just imagined the scream part way through with chris wolstenholme doing it)
DONT RISK IT, BUY A BASS AMP
#4
Beck did Little Drummer Boy (Little Drum Machine Boy), but it'd be cool if Radiohead did something, it wouldn't matter what song.
Animal Collective doing Ukrainian Christmas Carol would be neat.