You do need to take the air train. There are 2 stations for the air train, one on each side of the long term parking lot. The walk wil depend on how busy it is but is no longer than a shopping mall at busy times. If you have a lot of bags, there is a drop off area before you park. You do not need a reservation for parking. From the air train stop for Jetblue to the terminal is about a 5 minute walk, all in doors and only 1 way (no way to get lost).
It is not difficult at all just leave yourself enough time. Leave yourself about 40 minutes to park the car, catch the train, ride the train and walk to the terminal.
LTP to Jetblue