Apple reserves the right to keep their cut, but doesn't seem to in practice according to other devs I've spoken to. AKAIK no-one's asked for a refund on Alien Swing yet so I can't speak from personal experience. I imagine they might keep it if the Dev was doing something particular egregious to cause loads of refunds.
One, but i should get two. First one because they charged me for a freebie. I didn't claim the other one. It's been a long time (last summer i think). Should i try to get the other one?