Question from Dawnguard newbie. Have wandered around the fort,then was sent out on the Awakening quest--back to Skyrim.
Is there a town for Dawnguard, where one can purchase and sell, interact with residents? (i.e., like Solhstein) Or, does each quest send
one back to Skyrim?

Only inside Fort Dawnguard, when you have done a certain amount of quests.