Yes, the calendar, in my experience, changes exactly at midnight. The salmon dial is absolutely stunning as well and I hesitated quite a bit but I have a Patek 5270P with a salmon dial and I try to keep internal competition within the collection to a minimum so every one can get along .
It’s a bit on the heavy side but since it’s fairly wide (44mm diameter) and flat, it sits nicely on the wrist and doesn’t move around like top heavy watches. The full platinum bracelet also helps a lot with the overall balance. I would guess that the same watch on a leather strap would be very unbal