[taylorc]

I would not recommend using the park position on the gearbox as the only brake as you are relying on the transmission to hold the car (which increases wear on the gearbox), you can get away with it for a short time but for parking up purposes it is best to use the electronic handbrake.
This leads me onto the next question.... I am not aware of a way to automatically apply the electronic handbrake when the engine is switched off but you can dis-engage it by just pulling away, as the torque rises it dis-engages the brake (you have to be wearing a seatbelt though).