Thanks guys, for your time.
As far as resolution goes, I need it to be as fine as possible. What if player A's attack lands on player B's camp at nearly the same time as player C's attack? I want the first attacker to take the loot, so I need to update the defender's records before the second attack is resolved.
I think I agree that a websockets/node.js solution is called for. However I am running a Zend PHP server which has some job queue functionality, so stay tuned.
Thanks again.