No! We have taken care of the viewing fee, you will not need to purchase anything to enjoy the Fantasmic Dessert Party.
If you do not have a car and are staying on Disney property, you can take the complimentary Disney transportation to any of the locations! If you drove down, you will be able to drive and park at The Grand Floridian for the ceremony, The Boardwalk for the reception and Hollywood Studios for the dessert party. If you aren't a Disney resort guest, you would have to pay to park at Hollywood Studios. (There are ways around this if you want to text Chelsea for ideas)
We do have a room block for discounted rooms for our guests at Disney's Pop Century, Coronado Springs, Art of Animation and Grand Floridan! Find how to book on the Travel portion of the website. Staying on property will be easiest for getting around to the wedding events and the parks.