So before the dlc came out there was talk that you could get new player housing depending on the side you choose, could some please tell me what these are exactly, if you can upgrade them, and if you can move there with your spouse.

a cot or coffin in either a fort or castle...thats your new housing

Faction bases with minimal upgrades, most of which come automatically. I do not believe your spouse will live with you.

No, your spouse will not move into either Castle Volkihar nor Fort Dawnguard.