Is it possible
 

To seperate the words from some music so only the instruments can be heard?

Yes it is, I think thats how all these instrumentals came about on like kazaa and such. I have no idea how they do it though.

If you've got a master copy of the song you're looking for, maybe. I'm not sure if you can remove tracks once a song has been mastered. If you're just looking at editing an mp3, I'm not sure.

Those are probably Karaoke versions ;)

You can't seperate a song that's been recorded as one audio stream.

Actually, I think their are programs that can do that some what. They separate the different sounds, but im not sure if you can save them separately.

I seen it on CSI, and im pretty sure that programs like that do exist. They all use them for deciphering the black boxes after plane crashed.

I think, I might be talking Crazy... that with CD's (maybe just old CD's), you could cut a certain wire on a certain stereo and not here the vocals... I might be psycho though.