Hi Jackie!
For lunch or dinner, a Quick-Service Meal on the Disney Dining Plan includes an entree, dessert and non-alcoholic beverage. If the entree comes with a side (like a burger and fries), that's also included as part of your meal.
Starring Rolls Cafe is a great choice for sandwiches or sushi at Disney's Hollywood Studios and I've dined there many times myself. You're exactly right about what would be included: a sandwich with your choice of fruit or chips, a beverage and one of the delicious dessert choices offered. For fountain drinks, I've always received the large size, but if you have a preference just let them know when you place your order. The Cast Members are also great about knowing exactly what's included on the Disney Dining Plan, so if you ever have questions, just ask!
Here's a link to the
2014 Disney Dining Plan brochure, which should help as you make your plans, or just stop back by the Disney Parks Moms Panel and we'd be happy to answer your questions! Wishing you a most magical vacation!
Beth