Prop reverse
(throttle to idle, click reverse handle, allow plane to slow down, throttle to idle to go back to forward thrust)

The passenger door
will open and airstairs will extend when you press Shift-E. Press Shift-E again to close the door for flight.

The working cowl flaps
are opened by Ctrl-Shift-V, and closed by Ctrl-Shift-C (both in increments).

The landing lights
light the ground properly, and must be extended before use (press the L key, and then press Shift-W). There is a separate taxi light on the nose strut (turns off with the rest of the lights using the L key, or use the switch on the panel).

The prop blades
actually rotate when you change the pitch or feather them; to feather the prop select engine by E1 or E2, then press and hold Ctrl-F2. Press M--- and Ctrl-Shift-F1 to shut down the ignition and mixture. Then press E2 or E1 so you can operate the other engine.

Contrails
whenever you want them (press the I key)