I'm sure the Greater Belfast area will have a good TG4 signal, not that there may be much of a demand for it in places like Lios na gCearrbhach, Carraig Fheargais or Baile Nua na hArda...
Shame TG4 was pulled off Sky Digital after it lay there unencrypted for ages until it was mentioned here...
During the 1970s there was a healthy debate as to whether the second Irish transmitter network should be RTE 2 or BBC 1 Northern Ireland... eventually RTE 2 was what happened (thanks mainly to good lobbying on the part of RTE), although I bet many people wished BBC 1 had happened instead...
All the channels will not be available north and south via analogue. There is no way room for nine analgoue TV networks on the island anyway. They may well be via digital terrestrial at some point in the future but we will have to wait and see (IF there is ever DTT in the south).
As for a BBC Ireland, they would never be allowed set one up, nor would the BBC want to.