Its SO exciting isnt it!! We go in 5 weeks, cant wait 
Tips,
defo visit Walmart for food shopping (car tyers and guns if you need one..i kid you not!) We took sarnies and fruit and drinks with us into parks as all they really serve is greasy burgers & fries, we got fed up with junk food.
Buy bottles of water, pop them into the freezer the night before, and take them out to take with you to the parks, they are lush when defrosting when its hot.
Its cool in the shops as the air con is very good, you may need sweaters.
Get "fast passes" for the rides in the morning when you get onto the parks, as you end up in lines for a couple of hours for the most popular rides. Not fun with little ones.
Park tickets are not cheap,many offer multi park tickets, so check. Sea world for eg offer equatica too, well worth going, awsome place.
Give yourselves a few days off, honestly you will be absolutely wrecked as the parks are huge..i mean HUGE, impossible to get round in one day. you need rest days at the villa to just potter and enjoy your pool. (do laundry and relaxxx)
Magic kingdom opens till late, its well worth satying for the fireworks and the parades are fantastic, go back a few times.
Budget for car parking, you have to pay addittional car parking at every park, it can get expensive.
ENJOYYYY!!!