There is surprisingly low information regarding soundtrack to these great games. Are there are resources you can link to that can eleborate on the subject a bit more? I mean we know the composers but I have no not even idea whatsoever if all the tracks are original compositions. There is one post with oppinions here but that is about all i could find.

This is for I thru IV, but it has some basic info.
http://www.celestialheavens.com/forums/viewtopic.php?t=11323&highlight=music