Thanks for the awesome, and complete reply! I primed the room with an exterior latex primer prior to reading your post. Hopefully everything will be fine over the coming winters.
I saw a reply by Nestor Kelebay about _not_ using _interior_ paint for the walls of a three-season porch, AFTER I had primed my porch with two coats of interior primer!
What should I do now? Do I prime again with a exterior primer? I also primed the ceiling. Not sure if it matters, but I...