I think your $300 food/entertainment budget is vastly underestimated.
Chef Mickey's is going to run you close to $175 after tax and tip.
I don't know how familiar you are with FL, but the Melbourne Zoo is not anywhere near WDW. I have a lot of family that lives in Melbourne, so we always combine our Disney trips with visiting family. It takes an hour or more (depending on how fast you drive) to get to Melbourne. I think it's about 70 miles each way, give or take. There are also tolls involved. Figure on adding about $30 to your trip for the gas to Melbourne. Now for the cost of the Melbourne Zoo. I love zoos and animals, so I thoroughly enjoy that zoo; however, I think it's the biggest rippoff I've ever been to as far as zoos go. It's small...if you spend 3 hours there it's a lot. The last time I was there (March 2007), I think it cost us about $35 for four people to get in. Since you'll be paying for 6 people at half price, figure on another $25. That brings the cost of your zoo trip to around $50 (gas and admission)...this assumes you bring all of your food with you!
You're down to only $75 left on your food/entertainment budget after just these two expenses.
Pressed Pennies...you included this as an activity, so I assume you aren't planning on just letting each kid make one penny each. At $.51 each, pressed pennies for 4 kids is going to add up pretty quickly.
Even if you're only planning on spending a grand total of one hour at the arcade, it's going to be AT LEAST $10 to entertain 4 kids for that hour. That's assuming you only let each kid have 10 tokens (and very few games these days take only one token each!)
Another thing I'm wondering is if you are going to run out of things to do. It doesn't seem like you have enough things planned to fill two weeks, unless you're planning on just relaxing at the pool on most days. This is just my preference, but I'd probably swap out the
MNSSHP and Epcot tickets for some Universal Studios Tickets. It would cost you LESS to get the US tickets, and they would be good for unlimited use for the entire week. The Epcot and MNSSHP tickets would only give you one day plus one evening of entertainment.