1) I drive a GT so no idea on this.

2) I have maybe 2-3" movement after using park only, depending on the incline. It doesn't have to be a huge hill to make the car move a little, and since I just got my transmission totally rebuilt I'm going to say this is normal.

3) My car sometimes did this when coming out of park. It's usually if not always caused by parking with just Park on a incline, even a slight one, because of the pressure exerted on the pawl holding the car in place. It is possible to even "lock" the shifter in park from that pressure alone if the incline is steep enough and then you won't be able to move the lever at all. From what I understand the correct procedure is ebrake on, THEN shift to park. That's what I almost always do on all surfaces and I really haven't noticed this happening since.