We're not in Halifax, but in NB, and we use Bangor for our departures all the time. It is just not financially feasible to pay 3-4 times the price for the privilege of flying out of Canada for us.
I think it would be about a 7 hour car ride to Bangor from Halifax, so a hotel will definitely be needed in Bangor. We have stayed at the Days Inn, which offers a shuttle to the airport and you can leave your car (with the keys) in their parking lot for $2-3 a day.
I'd recommend the Sheraton Bangor. It is a little pricier than the other hotels but it has a skywalk to the terminal and has just been renovated and looks very nice. You can get a 7 or 14 day park- n - fly for $129 or $149. On the way back, it may be cheaper to get a hotel in Moncton or Fredericton than in the US.
Bangor is a very small airport, but most times everything runs without any delay. We have always used Delta, but if you want to rent a car in Orlando and save a little more money, you can fly Air Tran into Sanford. They have Bangor direct Sanford flights available.
Good Luck