I take it that we can use the Vorbis OGG with our own custom music tracks to edit the music? Is there a file that details what music files are used (I know that not all of them are used in the main menu, so it makes me believe there's a sort of text or data file that has all the music tracks laid out with titles and lengths and other info on the tracks themselves)
I'm pretty sure that the engine just scans the appropriate music folders for ogg files and plays them randomly.
IIRC, The only ones that get treated specially are the ones not in the main "in-game" music folder.
I believe that those require specialized names, like title, gamevictory, gameloss, chase, and other such music that is not played normally but only in special circumstances.
So I think you can just dump what you want (with vorbis encoding in an ogg file, of course) into the in-game music folders and the game will be willing to choose them.
I could be wrong though.
Make sure you keep track of expansion specific folders though. Expansion specific music goes into a different folder then the base-game music. The game "consolidates" all the the various in-game music folders across the base-game and the expansions into one big list that it will choose randomly from.