I like it! I like that you've got the Goods, the Bads and the Innocents. Always a good dynamic for a showdown.
Something to think about though, is you talked about returning to Heaven. How can they do that? You talked about how they had been banished for effectively mutiny or treason against God. Is there actually a way to redeem oneself from that? Are there angels that were just caught up in the plot by association and were punished because of their loose connection? Where would they fall? And the ones that cause chaos and panic, what should happen to them? Is there a consequence for their actions? If there is a Heaven, is there a Hell too? Or at least a "not-Heaven"? And do these agents of chaos go there? Who else is there? Can an angel go from one side to the other? Can an angel actually be neutral between them?
The whole structure and the rules and restrictions that you've placed, especially with the angels interacting with mortals, is brilliant. And the distinction between the two factions of angels is fantastic.
The things I'm thinking of are more about the mechanics of consequence and reward, and also surrounding alignment, but apart from that, I really am liking that idea.

sounds pretty interesting... although I don't know how it would work as rp... sounds more like a storyline to me xD