sounds good starting point, lot of possibilities there. Now, how many players and what kind of group combination are you looking for?
My take on those two questions :
#of players: MAX 4 (me included *smiles*) 3 would be ideal (again , me included)
Combination: What ever they feel making. (that way there will be variation AND group will be lacking of something.
Then I have an suggestion, for the running of the game. Each player gives the "themed song" about their character (like was suggested) and then give 3-5 other songs they feel fitting for the campaign (to give you tools and ideas what they are looking for) And ofcourse, keep it lv1 at the start. Giving out levels at the start is to call in those who want to min-max.