1. Try to find a balance between the two positions. Or work on your core muscles and flexibility so that you can lean over a little more. This may help you be able to move your hands around and find a comfortable position on the drops. (I don't have any experience with Campy shifters) Discomfort in the drops may also be because you are at your reach limit on the hoods, and when you're on the drops you're past your comfortable limit. Maybe consider raising the bars or using a shorter stem?

2. Go with 1/2cm. Make fine tune adjustments to your saddle height until you get it right. Also check the tilt of the saddle. Or it could be because you're sitting on the edge of the seat to compensate for the extra saddle height instead of sitting where you're normally suppose to.