Depends on what you book with them. In our case to get the rate it was a non-refundable ticket. They do offer a choice of airlines depending on where you are departing from and a choice of refundable tickets that are added on to your price of the cruise that do not have to be paid until your PIF date. Depends on your budget.
They do not sell anything less than economy and in our case with Alitalia we get a personal item, a carry-on and a checked bag included. We were able to select our seats already. You can upgrade directly with the airline should you chose. We got a great rate and Disney security, so for our first experience overseas and with Disney Air, so far, I am pretty happy.