There is the AirTrain that loops around the airport and makes a stop at all the terminals. Every stop at the plane terminals is free. There are also free shuttle buses from the car rental place to the car rental places are Federal Circle. Though both exist, I think the train is better and faster.
Yes there are shuttle bus pick up in the rental car and take you to the terminal
There is a free shuttle train going from AVIS to terminals.
Yes you have a free shuttle or train
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