ninrigger,
I have used wax for making masters and resin for my molds
http://i614.photobucket.com/albums/tt226/zbasser/baits/creatures/35ZGRUB.jpg
That is a bait that was wax master and resin mold. No spraying involoved of Pam or otherwise.
Wax will melt off almost completely when the resin cures. Your mater will be gone, but you already have a mold of it.
As far as using clay for a master in a resin mold, I have not done that. I might suggest not spraying directly on the master a you may get more of a mess then you want. Try brushing it on with a soft hobby brush. It should give you a glossy finish as long as it doesn't soak in the clay.
The smell factor is one that I don't understand. I have not had a smell transfer that I can detect from a cured mold. resin Gets hard quickly, and you can pour in it. It takes a day or 23 before it is fully cured. After that you should not have a smell problem. I have not found that talking fish yet that can tell me if he can smell rein in my baits or not. But have caught plenty of fish on my baits.
Hope that helps.