Breeding Loan Question

Besides the normal: I give you my males/females to breed with your snakes, what else goes into a breeding loan? Is a payment made upon successful birth of live babies? Do you split'em 50/50? What goes into doing a breeding loan? Thanks everyone!

All those details are completely dependant on the desires of the people involved in the trade and should be worked out and ideally in writing before the loan is started.
Some factors that will have a bearing on the outcome will be the animals themselves. Does one party have a homozygous animal and the other a het? Will one do all the work, housing and feeding the adults and incubating eggs etc while the other only provides one of the snakes? These things can affect the nature of the breeding loan.
It's really just up to the two people involved and what makes them happy with the arrangement. The clutch could be split, or sold and the proceeds divided.
The best thing though is to get everything in writing, even if it's with a good friend. Also included in the written "contract" would be what will happen if there's an odd number of hatchlings, or a very skewed sex ratio. Also what would be the responsibility if any should one of the snakes die. Trying to limit any unforseen circumstances will go a long way toward avoiding any hard feelings or problems arising after the babies are born.