We are currently addressing some of these issues in our attempt to create a statutory road association.  I think one issue is whether they are receiving some form of payment. We were told that if a member performs work on the road for payment --- even if the payment is only for expenses (gas, equipment, etc) or offsets their assessment, they would be considered a contractor and should have commercial liability insurance for their protection and the Association's.  Sorry don't have any input on your other parts of the question.  
Vicky