I can vouch for the fact that (at least some) forts respawn. I've been punking around with Fort Blueblood (near Leyawiin) for awhile now and the bastards respawned on me.
I'm still playing, but I'm starting to get frustrated. I'm level 4 now and still getting pwnt by everything. I got the daedra quest to get what her name's eye, went to the cave, and got 2 shotted by one of the trolls in there. Which probably means I'll need to be level 6 or 8 before I can complete that quest.
Fort blueblood (for the mage's guild quest) is also damned hard... probably a bit beyond my level still. So I can't complete that portion of the mage's guild quests.
Bleh...anyway, I have a funny feeling that I'll be dropping this game once an alternative comes out. Spore is nearing release. Assuming it doesn't get crappy reviews and doesn't have horrible DRM, I may pick that up.