As far as the freerolls go, I think if a player doesn't play in the tournament he is wishing to be staked for (maybe the stake wasn't completed on time and he didn't get the coupon) then the staking agreement should apply for the very next tournament the person receiving the stake can play in.

With real money buy ins, that should ultimately be left up to the two involved in the staking agreement. Normally the money would be returned.