Try moving over to the chopper and pressing "E" not at my computer at the moment so can't check as I've just been exploring on foot at the moment (and repeatedly getting killed).
Yes that seems to work. Jump into the chopper move into the front of the chopper and look sidewards at the pilot/ co pilots seat and foot controls. You should then get a prompt on screen to press "E" to use.
After that, it's time to play with the keyboard work out the controls, but in general similar controls to moving the character.
W, S = is throttle
A, D = Rotation
Arrows= Movement
R. Click the mouse for follow cam, L. Click Lets u turn the cam.