You’re moderating a forum. You want two things to happen:
- you want a particular topic to be addressed in depth by people who have thought a lot about it and who have something to say that people will show up to hear
- you want the people who show up to engage with the speakers, freely and informally. You want to pass the mic.
You probably can’t have both of those things at the same event. The minute you hand off the microphone to a participant, your power to shape the conversation to the topic you care about evaporates. Now the topic–and probably not just during the time they’re speaking–is whatever the first person you pass the mic to says it is, and that may not be what most people came to discuss.
Passing the mic feels democratic, but it usually isn’t.
YoRocko! 
How about representative democracy, then? Get the questions in writing as soon as you can, then have a Q &A session built in for a set period of time. Let the questioners know how long that session is. Take the questions that will best lead back to your own point.