Hi Sandra!
I will say that watching Wishes! Nighttime Spectacular happens to be my favorite way of ending a wonderful day at Magic Kingdom! Experiencing the pyrotechnics and special effects that make Wishes such a magical moment is always a must do for us!
If you and your family are planning on viewing Wishes!, there is no dining plan needed! All you need to do is choose which location is the one that will provide the best view for you! We always stand directly in front of Cinderella Castle so we won't miss a minute of the special effects displays, nor Tinker Bells flight! Some guests prefer the walkway in front of Crystal Palace, or the bridge from the hub to Liberty Square... the choice is entirely yours. If you are looking to dine at Cinderella's Royal Table, which is situated inside Cinderella Castle, and view the fireworks, you do not need to have a dining plan. There are tables located near the rear windows, which provide guests dining with a limited view of Wishes, and they are definitely prime realty. You can request one when making your reservation, but it is not guaranteed.
As for Mickey's Very Merry Christmas Party, dates have yet to be released at this time. Your best bet for current information on when tickets will be available is to check out the
Disney Parks Blog.
Hope this helps you plan your magical vacation!
-Malanie