To get back to your question about licensing music - I've dealt with this in the past by working with music that is in the public domain. There's fewer options than if you were to pay, of course, but this music can be used freely for any purpose so if you find a song you like, it can be perfect.
The folks at
http://www.publicdomain2ten.com/ have compiled a nice collection, and you can also try Googling for other sources depending on the style of music you're looking for.
I think this sounds like a great idea for a service and it has inspired some new ideas for my own services, too. Thank you for sharing and good luck with developing this new part of your business!