Thanks for your suggestion. I wrote out some protocols for student volunteers and gave copies to my most active students as well as posting them in a prominent place. It has made things easier. I no longer have to stress over how to tell a well meaning student that their actions have been unhelpful or even detrimental to what our studio is trying to accomplish, knowing that they were only trying to help. Now, the best way to contribute (for those who want to) is clear and accessible and I can point to that any time there is a question or a problem.
I also invited my most committed student volunteer to attend our staff meetings so that he gets to have all his ideas heard and he knows how his actions can best support the studio. He loves it. He gets to feel involved, and I don't have to answer a bunch of questions from him later about how he can help.
Next step -- get everyone to start writing down their tensions and bringing them up at the appropriate time rather than just blurting out things whenever it occurs to them.