I definitely agree with the post above. Pooh’s Hunny Hunt and Monsters in Disneyland are must dos if you visit. Disneyland is great but a lot of it is based on Magic Kingdom so prioritise Disneysea if you are on limited time. In Disneysea must dos are definitely Sindbad, Journey to the centre of the earth, and 20k. Indy is a really good take on the Disneyland original (splash is the same as well). I love the gondola ride as well as its a perfect mish mash Japanese view of European culture.
snack food in tokyo is interesting, make sure to tey things like the green alien mochi, gyoza sausage bun and the flavoured popcorn and churros. Check the tokyo disney website for menus (I use chrome auto translate), IMO good bets are the country bear in Disneyland does good Japanese curry and Grandma Sarah in Critter country has nice food and you eat in splash mountain! Over in Disneysea Vulcania is often good and the Yuccatan base camp often has good specials.
https://www.tokyodisneyresort.jp/tds/restaurant.html
If you stay on site you can save money by staying at a partner hotel. I’ve stayed at the Hilton and Sheraton, both are nice the Sheraton is probably slight nicer. If you arrive by train you can check in next to the staion and get luggage etc delivered.
The rest of Japan is amazing- where are you thinking of going? The people are super nice I definitely recommend traveling beyond Tokyo if you have time check out getting a railcard if you travel around and get an IC card for metro travel. Use hyperdia
http://www.hyperdia.com/ to check timetables. If you let us know where or what you’d like to do I’m sure the people here can help with suggestions