I love All Star Sports. There is a big football field. Bring a ball with you if your kids want to play, because otherwise you will be stuck buying an overpriced mini one at the gift shop. The field can be a bit loud at night, but we always get a room on the field because my kids love it.
There is a mini fridge in the room. I would suggest a grocery delivery or short cab ride to get supplies. Breakfast at the restaurant in the resort will run you about $10 per adult, maybe $7 per kid. I found it better to get some muffins, juice, etc and have it in the room. Same with snacks in the park. You are allowed to bring food in, so just toss it in the backpack. As a PP noted, they will refill your water bottle anywhere they have water (some snack kiosks only have bottled drinks, not running water). There is also a MCDonalds right outside the All Star Sports, but a bit of a walk.
In the parks there are table service restaurants requiring reservations and expensive. There are also quick service places with meals in the $10-15 range for adults and about $7 per kid. The food is good, often basically the same, as the table service restaurants. Agree with PP that snacks are the way to go. There are some amazing cupcakes, I think in Hollywood Studios, that are maybe $4-5 and are huge and just gorgeous and decadent.
Disboards is a good online forum for figuring out all things Disney.
I give the kids an allotment for souvenirs, generally around $20 for the whole trip.
Not sure how old your kids are, but if either of them wants to do the Jedi experience at Hollywood Studios, get there early and get signed up right away.
I actually like it in the parks because I don't feel nickeled and dimed over every last thing. Food is more expensive at other parks, and the quality is better at Disney. The rides, shows, activities, etc are included and there aren't midway games and such.
Get your fast pass rides reserved as early as possible! Particularly the A category rides, like Soaring. Look at the map and lay out your day and ride times as efficiently as possible. The default times they offer may not be the best for your schedule, sending you for one end of the park to another each hour.