Hi there, Sonia!
You will get no objections from me, as
Mickey's Not-So-Scary Halloween Party is probably my favorite event at Walt Disney World.
The Fantasyland Expansion is rolling out gradually. Several features have already opened to the general public: at least one of the double Dumbo rides is operational, with the other in ride-testing, which means both sides will likely be open in October. And the indoor, interactive queue is also open to the public. The Casey Jr. water area is open, as well as the Carrolwood Train Station, allowing Guests to take the 360 ride around the Magic Kingdom by train.
More vague is the list of attractions that are slated to be open "by the 2012 holidays." No definite dates have been announced, but the next group of attractions to open are:
Under the Sea ~ Journey of the Little Mermaid
Enchanted Tales with Belle
Be Our Guest Restaurant
Gaston’s Tavern
Ariel’s Grotto
Again, no hard and fast dates have been released for these attractions.
Even without the Fantasyland Expansion being fully open, you should still consider a day ticket to the Magic Kingdom. With so many rides, attractions, and entertainment options available, you might want to give yourself the extra time to explore this classic Park at your leisure.
Have a wonderful time!
See you later, celebrator,
-Deborah B.