Hope you don't mind advice from a SOONER.
1. I have not noticed a great deal of difference between the front or the back as far as cabins go. Most people prefer middle of the ship, because of closer proximity to the central elevators.
2. Not in my opinion, they all go to the same ports.
3. Chances are very slim for getting an upgrade after you board. Basically all the cabins are the same unless you can spring for a balcony or a suite. Granted, some lower deck cabins have bunk beds, but in general, there is little difference between an outside cabin on any deck or an inside cabin on any deck.
4.Tips are billed per day, to your card.
5. 5 day cruise, $50.00, 7 day, $70.00 etc...
6. The beds will be moved together for a couple unless you request they stay apart. They provide plenty of room either way.
7. You can bring a limited amount of drinks on board. You could bring a cooler, a colapsable one is best.
Welcome aboard! Ask any questions you have, someone here will usually have the answer. Ecstasy is a nice ship, you should enjoy her.