I was there about the same time as Pholi, so can't help much with the costs etc, but it is AWESOME. You will however, want to take a VERY wide berth of the Small World ride!! That is painful!

The night parades are great, kids will love it. There is a Disneyland train station, so you can go straight from Tokyo Station to the park. JR have rail passes too, if you want to do other traveling while you are there - highly recommend this as it will make your lives so much easier (if you don't speak or read Japanese).

Food prices are like any other theme park in the world, so be prepared, I would take some muesli bars in your bag and some water.