Excellent post PC Guy,
I also agree with Jim about booking an Oceanview Gaurantee as a way to be gauranteed a cabin on the lower deck with an Oceanview and a very real possibility of being upgraded to a higher deck. It is a rare event to be upgraded to a balcony though.
If you are nervous about the ship's motion ask the Agent what is the price difference to pick a mid ship cabin on the lower deck. The price is almost always the same, you don't get an upgrade, but you get to choose your cabin. And the cabins are identical on the decks, just a matter of a few more seconds on the elevator.
The 5A Category Portholes are the same price as the Inside Cabins, but if you get any weather be prepared for a bumpy ride.
Hope this adds to the other posts and doesn't confuse you. As I know how confusing it can be.
You will love cruising!
Best to you, IslandCruz