Cool, so tell us about the three houses, what are the differences between them, who rules each, etc?

Are you born into your house, like it's a familial line thing, or can you defect?

How big are dragons?  Are they capable of artistry, forging etc?  Do they build houses, or live in caves? 

Can we play as humans?  What technology level are the humans, and what is their society like?  

Why has nobody ever flown across the sea?  Did nobody know what was over there?

There's a reference to other dangerous creatures living on Athea, what are they? Is it meant to be that they are dangerous to dragons?

How long do dragons live?  

Do they have writing, or just a sort of oral tradition?

Any other expansions on our knowledge of this world would be appreciated.  

EDIT: Oh, is there magic?  Or are dragons purely biological creatures?  Do they all breath fire, or maybe some have different breaths?