1. Torrentz > Warez > Limewire
2. You can get some really nasty viruses no matter what, but its unlikely. But generally, yes, you gotta be dumb to get common ones
3. Limewire, from my experience, has really low quality music with incorrect ID3 tags (when put into itunes/songbird/anymediaplayer, the titles, albums and artist names were either nonexistent or not set up)
4. Don't even get me started about album art (50 gig library, all high-res art and tagged correctly)
5. Limewire, to the best of my knowledge, is easiest to track.
TL;DR: Sayonara, Limwire. And good riddance!
Building a rail... slowly (time).