Zack,
The company will get you from your home base to your airplane to start the trip. It could be by airline, rental car, limo, etc. You will receive your travel info usually around 1800 the night before. Your responsibility is to be at your home base to start the tour (theoretically at 0001.)
On the last day, they are responsible to get you back to your home base by midnight. Otherwise, they have to pay you for 2 extended days (ie: big bucks).