No, the parking brake does not automatically engage in P. But if you engage it, the parking brake automatically disengages if you are wearing your seat belt and apply enough throttle.
Hill Start is not described in the manual as far as I remember. It's just something that needs to be there on an S-tronic car, otherwise it would be rather undriveable on hills as you would have to remember to manually engage the parking brake every time you start on a hill. It's not like with a manual transmission where you can hold the car with the clutch on a mild gradient or do a handbrake start. Hill Start engages automatically if you stop on a gradient of 3% or more and it holds the car for about 2 seconds.
BTW, Hill Start is not to be confused with Hill Hold (not available on US cars). Hill Hold needs to be manually engaged and holds the car indefinitely whether you are on a hill or flat surface. On a flat surface it avoids the creeping forward if you take the foot of the brake.
I felt the same way as you the first time I felt it simply pulling out of my garage, but after driving some hills, I accepted it as normal.
Last edited by superswiss; 03-11-2014 at 05:28 PM.