Welcome to the Disney Parks Moms Panel, Mary! I really wish I had exact dates to share with you, but the answers you seek will found in due time. I am also visiting Walt Disney World Resort this November and am anxious to start planning our trip. Park hours and schedules for nighttime spectaculars such as Fantasmic! are
usually published around six months in advance. In the past, Fantasmic! has been shown on Thanksgiving Day, but keep an eye out around May for its definite schedule. Once you have those park hours and schedules, you can begin making your daily itinerary.
Advance Dining Reservations can be made up to 180 days in advance. So, as you make your day-to-day itinerary, make note of some dining locations you would like to try, such as Mickey's Backyard BBQ. This barbeque buffet is usually held Thursday, Friday, and Saturday nights, but has been known to throw in some extra days mid-week. Schedules are always subject to change, but I know in the past it has been offered during November. I'll keep my fingers crossed for an extra special hoedown for you!
As for Mickey's Very Merry Christmas Party, its schedule is up to the big man himself - Santa Claus! Once we hear from him (usually around March or April) when he is available to leave his hard-working elves and stop in for a magical ride down Main Street, U.S.A., then the party's schedule will be set. Since you mentioned Thanksgiving week, I will say that this party is not usually held that week. If your trip extends into the week before or after, then you will have a better shot at visiting with Santa.
Again, I am sorry I couldn't give you exact dates, but I hope the information I shared here will guide you in knowing when to find those dates. Happy planning and stop in again anytime you have a question!
Brandy