What exactly is this app going to do? "Adding songs" can currently be accomplished with mp3tofid, which is what I've been using for several years to sync my music to my car. It already rewrites the database when it syncs. It doesn't have any UI for playlist management or adding/deleting songs, so maybe that would be novel, but mp3tofid has the advantage of running on the server where your music library is, whereas your phone probably doesn't have your whole library on it.

If I were in your position, I'd think strongly about starting this project off as a simple player UI app -- something that would show the current track details, maybe pull down album covert art from a web service, let you navigate tracks, use the Tweak/Hate functions, etc. If you get that done well before your deadline, the next thing I'd add would be on-the-fly playlist management, a la Palantir. The very last thing I would tackle would be anything that tries to mangle the database, as I don't really see what the phone is accomplishing unless it's somehow connected to your full music library.

Actually, if you *did* have access to your whole music library via, say, Google Music, *that* would be interesting... I don't think Google Music has much of an open API right now, but it might be easy to reverse-engineer at least the "pinned" tracks that are stored on your phone's memory.