When do AoOs happen, sequentially? Are they always pre-emptive? Are all actions that trigger AoOs interruptable? (This came to mind as I took the Improved Sunder feat with a character of mine last night - I'm trying to figure out how AoOs interact with sunder attempts, particularly considering that opposed attack rolls are required to begin with.)
Do available AoOs on a given round stack with, or replace, one's normal number of attacks? For example, if I have only enough BAB to get one attack per round, and I take an AoO before my initiative happens, am I still allowed to take a turn? Or was that my turn? Similarly, if I have an AoO opportunity after I've already acted, am I not allowed to take it?