1. Yes (both road and trail)
2. Yes
3. 5-10 times
It's very, very interesting being involve in races from "the other side". You learn a lot, see a lot, experience a lot.
Why all races don't have a "service requirement" like some trail races is beyond me. I think a lot of people could learn a ton and it would make running races better in general.
For those who don't know what this is, in order to run their race, you must first put in a certain number of hours in trail clean-up, race volunteering, etc. Needs to be verified work, etc.
I just genuinely enjoy giving back to the sport. Now, that being said, if I do volunteer my time, it's for races where I know the RD is doing it for the love of the sport or I know isn't making very much money at all off of it. I've been asked numerous times to help with a certain "large" marathon that is held where I used to live and I flat out refuse because I know exactly how much the RDs (husband and wife) are pulling in from this one race.