If it's truly for a private collector then model releases arent needed. If they were then you could sell it commercially. What I would recommend is a quasi-release that clearly states that this isnt for commercial release. That way the talent is protected if someone does try to sell it. They can sue/get a TRO to block it from being released or get decent damages if it is. No one with half a brain will release a movie without releases.
IDs are necessary to make sure everyone is at least 18. Again if its not commercial, there's no way this project will ever make it into the government's hands so no 2257 is necessary. And no one will release a movie without proper 2257 docs.
As for the actual filming, be aware that more than likely, unless you are shooting in Cali, the project might be considered prostitution anyway. Freeman protects porn production in Cali. No other state has legalized porn production.
Michael
PrimeTimeUncensored.com