This is a great topic for a documentary! Check out "The Way We Talk," it's about the filmmaker's experience with stuttering. I think the biggest misconceptions about stuttering are that it's caused by anxiety or shyness, and it would be great to include communication tips for non-stutterers (don't finish someone else's sentences, don't look away or walk away during a stuttering moment, just give people more time to talk. It would also be cool if you could interview Speech Language Pathologists - look to see if there is a university near you with an SLP program, as they'll likely have faculty with a specialty in stuttering. Good luck!