http://razielsdomain.forumotion.net/draken-orb-f98/
There is WAAAAAY too much to this fic for me to repost everything here. Read it over there and come back here to discuss it. For the sake of those who haven't read it yet, please indicate the current chapter and leave specific commentary in spoiler tags.
"Draken Orb" is, obviously, the main series and followed up by "Draken Orb Z". "Genesis of the Beast" and "The Story Never Told" (the later of which is incomplete) tell the origin stories of two seperate characters; while not pivotal to understanding the story, I recommend reading both... "Genesis" especially.
As for the "Draken Shorts", I recommend reading as far as possible into the main series before checking it out; a lot of the sketches, especially the later ones, won't make sense unless you know characters and story events.
I'm not too worried if you check out the "Official Soundtrack", though. Specific tracks likely won't make any sense unless you've read the appropriate story point (although some lyrics may provide foreshadowing).