Hi Helen,
It sounds like you are a girl after my own heart - trying to squeeze as much as possible into your trip.
Fantasmic is performed on select nights at Disney's Hollywood Studios theme park.
The park hours are not yet available for October 2011. I would recommend that you keep checking the park calendar on the Walt Disney World website which can be found
HERE around the beginning of April 2011 to find out what nights it is scheduled to be shown during your visit.
We attended Mickey's Not-So-Scary Halloween Party in 2009 and it was so much fun that we are hoping to go again this year. My Son thought that trick-or-treating in Magic Kingdom was so cool and we all loved Mickey's "Boo-to-You" Halloween Parade and thought that Happy HalloWishes fireworks were some of the best that we have ever seen!
I hope that you manage to attend Fantasmic, Cirque De Soleil and Mickeys Not-So-Scary Halloween Party during your stay and wish you a magical and spooktacular holiday!