I was looking at some plans and see that they try and make a flat spot around were the combing is . My question is will you have problems with a spray skirt sealing if their is a fairly harsh compound curve in the combing, high in the front and back and low on the sides? Or is this mainly for ease of construction? The reason I ask is i just started building the combing on mine and it has an dip in the middle. The picture should give some indication of how harsh the curves are.

Now that your deck is completed and the cockpit opening is cut, there isn't much you can do about the coaming profile, so I wouldn't worry about it. Lots of commercial boats have a bit of an 'S' curve to the coaming.

This is also an area where there is 'a wide range of opinions'. I try to make my coaming profiles flat if possible.
Other good builders don't think it's an issue at all, and some prefer the curvy look.

Bjorn Thommason has a good (IMO) discussion of this issue on his website:

http://www.thomassondesign.com/en/news/cockpit-rims