Hi there, Mary! Thanks for stopping by the Disney Parks Moms Panel. I always love the chance to help out a fellow Floridian!
Kicking off the summer at Walt Disney World is so much fun, and it sounds like your plans are coming right along. My family has taken advantage of the Florida Resident Discover Disney ticket offer in the past, and found that it's a wonderful, affordable way to enjoy multiple days in our favorite place. With your Discover Disney tickets you absolutely can leave and return to the same park on the same day. Just keep in mind that if you want to enter a different park that day, you would need to add the Park Hopper option to your tickets.
You are welcome to bring your own drinks and snacks into the Walt Disney World Theme Parks, including water, soda, chips, sandwiches and pretty much anything that doesn't need to be heated. You can even keep your snacks chilled in a small soft-sided cooler if you like. You'll find a list of items you can't bring along on the Park Rules and Regulations page that will help you determine how to pack for the parks.
I hope this helps you enjoy a magical summer week at Walt Disney World, Mary. Please stop back by if we can help you with your plans. It's what we do best!
Kathy K.