The rotations are set up by the age of the children--families with young children are in one rotation, middle aged in another, and adults/teens in another. The exact age cutoff changes on each cruise as the cruises differ in the ages sailing. The basic idea is that a party of 4 adults probably doesn't want to sit in the dining room with a bunch of fussy toddlers.
That said, you can request a rotation prior to boarding by having your TA call
DCL. Your rotation will be printed on your KTTW card when you check in. If for some reason you are unhappy with what you have, you can go to "Dining Changes" and request a change. The staff tries very hard to give you what you want, but again, no promises.
You can request early or late seating....early fills first, so the sooner you make this request, the better. There are 3 restaurants, so on a 7 day cruise, you will eat in each one twice and the one you start at you will have for an extra night. You eat breakfast and lunch any time/any where you desire. The choices are posted on the Navigator that will be placed in your stateroom each night.
You do not need a cooler, although some people like one to take on excursions. Soda used to be free in the dining room, charged for at the bars. You could buy a mug and a soda package. However, sodas are now supposedly free all over the ship. Other non-alcholic drinks (fruit juices, milk, tea, coffee, etc.) were always free.
You will pay for alcohol, smoothies, snacks purchased outside theatres (you can always bring your own, get cookies from room service, or just not eat in the theatre). Tips to the wait staff and room stewards are not included. Basically, you can go on the cruise and have very close to NO additional expenses except tips...or you can spend a gazillion dollars on extras. It is totally up to you and what you choose to do. Shore excursions, photos, souveniers, alcohol, smoothies, arcade cards, etc. can all add up quickly. We don't allow arcade games (they're cheaper at home, and we didn't cruise to play video games...besides, there are limited numbers of free games on the computers in the kid areas). We take lots of our own photos and buy very few professional shots. Most shore excursions can be booked more cheaply on your own than thru DCL.....
Please ask questions here....and have a great trip.