Playlists should have a 'date added' for each track

I just changed the order of songs in one of my playlists, but now I can't undo this to revert to the order the songs were added to the list. It would be good if each track had a 'date added' listing. Ideally it would be nice if it also listed the name of the user who added the track for collaborative playlists and a note box for the user to add comments.