anytime you download something, regardless of where its from, it can be a virus. you just cant be a dumbass about some things and read comments (if there are any)
as for if it stays in itunes.. what the hell are you talking about.
you find the torrent, click download. it opens up in bittorrent or whatever the hell program you use (i use bitlord)
the file downloads, it gets saved to a folder. you find the folder, find the song/movie, and import into itunes.
repeat.