Is there a vodacome cell phone shop close to the hotel or in the airport to buy minutes on our Tanzanian cell phone?
Yes to both. The hotel is on an intersection with shops along the road to the airport and you can usually pick up prepaid vouchers in one of the stores. Sometimes, there are street hawkers around also selling phone cards. Finally, depending on when you arrive, the airport shops if open may also have them (although I've never bought them there).
Get an answer from Transit Motel Airport staff and past guests.