In other competitions I have been associated with, the competition directors would take questions via email and reply (to those worth replying to) in an open forum. This allowed a simple method to ask questions and that information not to be private but to be shared by all participants.
I would suggest you open an email address (AVC@sparkfun.com comes to mind) to handle AVC related questions. That email address would be read by someone who can speak authoritatively about the competition. They would answer not by direct return email, but rather via a read-only thread on this Forum. That thread would then end up becoming the addendum to the rules as well as a FAQ of sorts.
As an example, I have a few questions/comments for next year's AVC:
1) Will there be one? (Please say yes, I am investing heavily in equipment...)
2) Will it be about the same time of year?
3) What is the estimated height of your building? (To aid in determining GPS error due to building masking.)
4) I would suggest a maximum kinetic energy (1/2*m*v^2) for safety reasons. Videos of those propeller driven planes scares the pants of me!
5) I would also suggest a kill switch for ground vehicles over a given kinetic energy. 30 pounds at 1/4 mile per hour will cause less damage than 1 pound at 2 miles per hour.
6) When you say no environmental markers, would that include a DGPS base station sending out corrections over ZigBee or the like? If a private DGPS base station is not allowed, how about public DGPS?
7) Did your barrels come red or did you paint them? If you painted them, do you have the brand and color of the paint you used? If you did not, where did you buy them?