I think it may depend on what country you are in. Here in the UK the photographer has sole right of copyright, so no one can sell the photographers work (legally) without permission. Although where a third party or private land/property is concerned, it would depend on the original agreement. In your case I would think that a profit share would be a good option, although I dont think you are obliged to do so. As for the split, that is something you have to agree on, in cases like this I usually go for a 70/30 split in my favor, because there is much more work involved on my part. I never produce any photographs of people without a written agreement,(model release) this can save problems arising in the future.

The Truth is Out There