Well, I play on Heavy (or Maniac - 'cause half the ones I play are Japanese mixes on a modded PSX) and I'm at about an 8-foot right now. I actually don't own DDR myself, my friend does and he also owns two Red Octane Metal Pads (
http://redoctane.com/redoctanemetalpad.html), so playing with him is generally as good as playing in an arcade (though we do that from time to time as well).
I've been working my way up (skill-wise) for a few months now. But I only get to play it like, once every two weeks for maybe an hour.
I'm not sure what my favorite song is. If you're talking about dance steps I really like
In the Navy,
Heaven, and
Shiny Disco Balls. As for favorite music in the songs, I really don't have one.