As far as what is fair in dividing the babies is concerned, it depends on the prices of the breeders, if you ask me.
Say for instance, you want to breed your albino to someone's normal. If an adult albino, at that time, costs $5000 and a normal costs $200 then 25 babies should go to the person that owns the albino for every 1 that goes to the person with the normal.--the same ratio as the price of the parents 25:1 (these prices/ratios should be considered at the time the babies are to be divided in my opinion as prices can fluctuate considerably from the time of breeding loan until babies are produced).
If you are breeding normals to normals, there are 2 ways to consider it. Generally 1/2 the babies plus 1 is a good formula. The person who is taking care of them should get an extra one if there is an odd number of babies. You can also consider food costs and such and include that as part of the equation (you supply 1/2 the food and they supply 1/2), but basically, it's a contract so just do what you think is fair, and if you think it isn't fair, suggest to the person that you are dealing with that you reverse rolls and see if they are happy with that deal instead. If they don't like that deal, then it probably wasn't fair to begin with. Another way to consider it is to keep track of everything. This can be a real pain, but if you do it that way, very little is left to interpretation. Keep track of food costs, heating costs, etc. Then sell all the babies and subtract the costs from that money and divide by 2. Kind of messy.
And most importantly, write the deal down and list every possible outcome you can think of in the contract and how it will be handled! That includes no breeding, one of the breeders dying, a loss due to fire, theft, etc.--and make sure both parties sign and date it and have copies. You could even sign the contract in front of a notary public if it is high end animals or you don't trust the person.--You also need to consider the sex of the babies as certain morphs are far more valuable as females (or males). I wouldn't want to get 2 male pastels and the other person get 3 female pastels! You could even ask for collateral to make sure you get your breeder snake/babies back at the end of the contract.
Rodney