I really do not see a difference about doing the parks before or after the cruise. Personally, I like to do the parks after the cruise because with Disney, the cruise acts a bit like an opening of Disney magic. The Disney Cruise is great, but its still not as magical as the parks.
I would also be careful about what you decide on doing on your own. I learned this the hard way on the European Disney Cruise in which we did NOTHING in Sardina since we made port on a Sunday. We should have done an excursion. I would highly recommend doing excursions from the ship due to Disney Cast Member going on it, you know its legit, and you will be safely brought back to the ship.
Other than that, I agree fully with your special guest!
Also, I have talked to people who have both felt and not felt the ocean currents and a rocking ship while on a cruise. People I know have experienced rocking even on large ships, can this happen or will a large ship defray the uneasy feeling?
What else? How about Ginger Gum?