As far as insurance I'd ask him for copy of the policy and contact the insuance company directly to varify he's covered to work out of state and the policy is in force. Get it in writing from the insuance company, do not just take his word for it.
As far as the licence he's going to need a MA licence to do the work.
MA is very strick on who does what.
A simple call to the building dept. can varify what he's going to need.