The "jerk" you feel when you take the car out of park is what happens when extra load is put on the parking pawl located inside the transmission, which happens when the car is put into park on an incline, therefore the park brake is to be applied to take the wieght of the car off the park pawl. I suggest you get the park brake fixed.

The groan you hear after starting the car and start to move is an ABS system check the computer performs, perfectly normal.