Hi Judy,
In order to visit
Epcot and Mickey's Very Merry Christmas Party at the
Magic Kingdom Park on the same day, you would need to purchase a
1-Day Theme Park Ticket and a Special Event Ticket for
Mickey's Very Merry Christmas Party.
As far as the highly anticipated
Rivers of Light nighttime water and light show at Disney's Animal Kingdom Theme Park is concerned, we are still awaiting an official announcement to confirm when the show is due to debut.
I can tell you that dining packages were available to book for this show prior to the opening being postponed and because of this, I would think that it is highly likely that dining packages will be available to book once again as soon as an opening date is announced. My best advice to you would be to keep a close eye on the
Disney Parks Blog as this is where further details are most likely to be revealed.
Wishing you a magical trip filled with memories which will last a lifetime!
Emma