As for all that, I'm not entirely sure. But I'd wait on something like that until you've built into the game some. I got ahead of myself when I first attempted to hack Final Fantasy and did some music editing. I got very frustrated and quit. I'd look into more level editing and toying with game mechanics before you look at the fine polish of it all. Besides, deciding the tone of the game helps make the music selection/creation process easier, because then you know if the game is edgier and more hard core, or if it's simpler.