Hi,
Answering the questions in the wrong order, but......
Yes there are already connections between Zanzibar and the more popular National parks and Game reserves, both in the north and south of Tanzania, Daily flights link to the southern circuit via Dar es Salaam and to the north via Arusha, several operators on both sides.
As far as I am aware you would have to be on the Tanzanian register and a Tanzanian Air Service License to operate internally in Tanzania, but could operate from outside in to either Zanzibar or Dar ok, Also for foreign registered planes on Charters etc the navigation and landing charges are very high.
Part 66 maintenance I dont know about but I suspect not, many Tanzanian operators go to Nairobi for maintenance anyway.
Best
Crash