Hi Jessica!
Planning a visit to Downtown Disney on your arrival day is a great plan and something that I often recommend!
There are many dining choices for
Dinner at Downtown Disney. I'd highly recommend that you read the menus and choose something to reserve in advance online for your family since the area is very popular in the evenings. You don't want a long wait or disappointment on your first day of vacation!
With your
Water Parks and More Option on your Park Hopper tickets, you do have the ability to visit
DisneyQuest Indoor Interactive Theme Park and the
Disney Water Parks as well as 5 full days visiting the parks themselves. Should you visit DisneyQuest on Saturday, you'll STILL have your 5 full days remaining for parks Sunday through Thursday. You can also visit a park in the morning and a water park in the afternoon, or two parks in the same day on those 5 days, with the type of ticket that you've purchased.
I welcome you to visit me again as you think of further questions you have about your upcoming trip or if you'd like any recommendations!
Wishing you a simply Magical time at Walt Disney World Jessica!
Kirsten