If you book a Fantasmic package you will get a (usually very early) meal reservation at which you will be provided with vouchers for preferred seating at the Fantasmic show later in the evening. At this point it appears the vouchers are for the preferred seating area only. You do not get a specific seat or a special separate entrance to the theater. A half hour before showtime they will open up the preferred seating area and start doing general seating there, so make sure you arrive before that.
The meal consists of an appetizer, an entree, a dessert and a non-alcoholic beverage, or full buffet and non-alcoholic beverage if you choose Hollywood & Vine. Kids under 10 must choose from the children's menu at Mama Melrose or Brown Derby.