Hey, this is some good stuff. Just a few quick criticisms that I think could help out and mix it up a bit: first, the whole thing could stand to be 5 or 10 bpm faster. Also, rhythmic variation could be better... try syncopating some of the beats, so the stress is on every other beat instead of every three (FF8's Garden battle music is a good example). Your instrumentation and arrangement are pretty good, though.

As for your question: A Long Long Time Ago, UnknownOne (old music advisor) put together a document for (I think) Part I that listed the music we'd need. Really, if you're looking to write something specifically for a section of the story, you should go read it, since it'd be nice if the music matched up with the emotional contour of the scene (or, at least, what you think the scene will be like).

Ah. Character themes... that narrows it down quite a bit. :P

Syne's theme is pretty solid, as you can see from the recent rendition of the main theme (same thing). I've also pounded out pretty concrete themes for Ko, Brooke, Rush, Rheya, and Aequus.

I've had quite a few different ideas for Dell, but he's still pretty much open, as is Enna. Her theme was originally going to be (appropriately) a 6/8 modification of Syne's theme... now I'm not so sure about that, since I've modified that original theme.

Just like for story, then, the best place to go to get ideas for the characters is their character profiles.