Mp3 is against google's tos, so better find another ads provider. You can try cpm programs or other ppc like adbrite and bidvertiser.
well, i got my adsense account from my private game server, google approved me and use it to my different sites.
I have been accepted easily for my 20 days old site too. Just follow few steps 1) Hire a write or rewrite and ask them to write few articles for you. (20+ articles) 2) Just post few articles links to digg, stumble and many social bookmarking site Then apply for adsense you will be approved