I agree with Karrot - the best thing to do is do some research on here, read some of the threads on different makes (i.e. are you only interested in Real Dolls?).
We're a pretty relaxed bunch. I've had a couple of positive experiences with photographers - but I think that's a different medium to film, which as dollman2 alludes to, the emphasis can easily be shifted in editing and post-production.
Midiman is the guy to speak to, as a fellow documentary maker. Although based in Canada, and spends more time over on TDF. He might be able to smooth the way and give you tips on how to go about your project.
PS Welcome.