My only rebuff against this is that the Mythal->Dumat->Andraste->Flemeth connection is too strong.
Reposting from here:
Dumat being the Dragon of Silence also works because Mythal had been murdered and betrayed and thereby the first God to fall silent.
And Flemythal stating that she knows Corypheus better than we might know would also make senses because he was the most devoted follower to Dumat.
EDIT: Snap. If that's true, perhaps that's WHY Fen'Harel gave Corpheus the Orb. He thought, hey, you're a devoted follower to Dumat who is Mythal, so here's the Orb! This couldn't go wrong!
I missed that comment of Flemeth's.
I like this theory. Hmm. Razikale and Dirthamen fit in so well into Razikale and Lusacan, though. Must. Find. Way. To. Evolve. Pet. Theory.
As for your theories on the dwarves, I'm a few pages into the Neat Timeline. Dwarves make first contact with the elves in 3000FA (Founding of Arlathan). King Endrin Stonehammer, three and a half thousand years later, moves the capital to Orzammar, builds arenas, names the victors of the Provings as Paragons, and is himself named the 'First Paragon' on his deathbed for his accomplishments. There is no mention of Paragons before hand. The dwarves form their alliance with Tevinter five years before the official creation of the Imperium, and fifteen years into Darinius's reign.
EDIT: Someone needs to find Solas's discussion on the Old Gods. Everything he says. Especially that one conversation with Cassandra, where we the players realize that Egghead knows what the Archdemons really are, and just isn't going to say anything about it.