Food budget depends on where you plan to eat. Counter service for children is about $4 to $8; $5 to $15 for adults. The lower end is a light breakfast, the upper end a combo with and additional side or dessert. Full service restaurants and character meals start at about $12 for children and $25 for adults, plus tax and tip. Many are higher. At some restaurants, your 1yo can eat off your plate at no charge. There may be an entertainment fee at character meals (we had a disabled young lady in our group last December who is on a feeding tube and obviously unable to eat, but there was an entertainment charge for her at character meals). Ask at each full service restaurant before you enter. The CM at the podium should know.
Most of the meals have very generous portions. If you are a light eater, you may be able to share with your DH or a child. Sometimes you can purchase a combo meal, an additional drink and possibly an additional side dish and save quite a bit of money. Just depends on appetites and individual food preferences.
You can improve your budget by shopping at a grocery store off site for some snack and breakfast basics. Publix, Winn Dixie or Albertson's are your best bet for good prices (WalMart Super Centre or Super Target are good if you have transportation, they're too far away for taxi). Goodings, an independent chain with a store near DTD, has very high prices on most things. Okay for a few snacks, but strongly recommend the other stores if possible.
Unless you're paying extra for it, you won't have a refrigerator in your room. If you're shopping off site, purchase one of those styrofoam coolers and use ice from the machines on each floor to chill drinks.
Bottled water is $2 for a 24 oz. bottle; $1.25 for a smaller bottle (didn't check the size--12 oz?) at the parks and resorts. The resorts also had a one litre bottle for $2.50 or $3--can't remember. Snacks in the parks start at about $2.50 each for Mickey Bars and go up from there. You can purchase snacks at the gift shops in each resort, park or DTD, but expect them to be higher than convenience store prices.
Hope you have a magical holiday!