You have had an accident. At this point the only law broken was the law of physics stating that two objects cannot occupy the same space at the same time. If you leave the scene then you have broken a law of man and could be in trouble for this. If not you are at fault for the accident but that's all.
From being parked only - no.
Garage
Yes.
your car cannot be reposessed if it is in your own garage
In brief, if they can get to it, yes they can.
The position that can safely be used if the car is parked in a closed garage.
They parked it in a parking lot.
Well yes, But if you lock your garage then the repo officer will have to come to your door in order to get the car.
Yes potentially
Hitting a parked car and leaving will more than likely have you ending up in jail. It is called leaving a scene of an accident. This can have heavy fines as well as jail time. You may have been caught on camera.
the person who parked the car
Yes. Quantum mechanic proves it.