To be quite frank, I intentionally didn't comment on your brainstorming (and won't for a while), as I want others to sense and react to the need of opinion. I think there is much more to be found in a combination of several to many opinions, than in the opinions of two or three of us. Plus, I honestly and deeply love the creative process, and can't appreciate it the same way when it is influenced by my hands :)
That said, I just spent the last few hours mesmerized by wikipedia articles on daemonology, especially when they drift away into D&D world stories. The Blood War's fascinating, and reading that the Illithid empire brought it to a hault, as the Lords of Hell and demon princes contemplated a joint effort against them, literally had me laugh in admiration for a second, then I stopped suddenly, in awe, as the meaning and implications struk me.