Hi Monica,
The Art of Animation food court is so much fun. There are loads of wonderful customizable dining options there.
You can get the complete scoop on the Disney Dining Plan by
downloading the DDP brochure from the Disney website. You are entitled to a non-alcoholic beverage with each of your meals, in addition to your refillable mug. So yes, you can get an "extra" drink with your meals. This could be bottled water, soda, milk, or juice. Unfortunately, the smoothies don't count as a drink. However, some of the smoothies available for a snack credit.
If you go to the independent website DisneyFoodBlog.com, you can lots of photos of the food court and the smoothie station. Search there for an article called, "Food Photo Tour: Art of Animation Landscape of Flavors Food Court" The items with the little purple and white checkerboard symbol can be purchased with a Dining Plan snack credit.
Good luck with your planning. Please let us know if you have additional questions.