A marathon is a Spartan's endeavor if there ever was one! I'd recommend not only cutting out booze, but replacing it with kale juice, or wheatgrass. Free radicals build up faster in the body that is put under severe athletic strain.

Also, gentler proteins! Peanut butter if you aren't allergic, and bananas (which are a runners best friend, and are cheap in most places).

If it were me, I'd throw some easy/classical in with the hard core stuff as far as playlists, but hey, thats your preference. I sincerely wish you the best. My first marathon was a tough trail run, and the best thing that came out of it was making a friend of a veteran runner (Rrrrick Karapostos, I probably killed his name but he does use a lot of r's. The man has run over 100 marathons, and does lots of charity work.)