My 2 Cents
The requests for information are reasonable. Ignoring them and being cryptic in the responses is not the right approach, Planning events can at times be frustrating for the organizer. Commitments are initially made by vendors, they drop out, come back with less than originally discussed the list goes on.
Do an A to Z review of the current status on all aspects of the event to date that are confirmed, were initially proposed along with the changes and additions. If it is a cost item estimate the cost from the quotes received to date with the stipulation that is it estimated and update once confirmed.
It is what it is at this point. If everyone knows going in what is confirmed instead of having false expectations or not knowing upon arrival it will make for a more enjoyable event and they can plan ahead. Anything else added can be updated and be considered a plus.
Communication is key. If the quarterback doesn't share the play chances of getting in the end zone are nil.
In the end you will be riding motorcycles, gathering with old friends, making new ones and doing something good for a charity, Nothing wrong with that!
It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood; who strives valiantly; who errs, who comes short again and again, because there is no effort without error and shortcoming; You can look up the rest.