So what were they and what happened? Kind've like the inca, maya, aztec civilinations?
http://www.imperial-library.info/content/definitive-guide-dwemer
What happened is still a source of debate.
And are the daedra/aedra just aliens? What if the teleportation to other daedric planes is actually another planet?
Anyone know this stuff?
The Daedra are, essentially, aliens, since they are not from Mundus, and Oblivion is technically outer space and what mortals see when they look at the sky. The realms of Oblivion aren't exactly other planets, they are infinite dimensions.
More on http://www.imperial-library.info/content/cosmology.