DH and I will be there, as well, for 10/18-10/25. There is a lot going on at that time. We were there at the same time of year in 2001.
The Food and Wine Festival is at Epcot starting on 10/18. Lots of great beer and wine tastings, food and wine booths in the WS, offering sample sizes of different foods from various countries. There are specialty dinners, but these are hard to get.
MK hosts Mickey's Not So Scary Halloween Party. We are planning to do this one night. While I have never been to this party, I have been to the Christmas Party at MK, and loved it! This is similar, but rather than Christmas themes, there is a Halloween theme, people are encouraged to attend in costume, and there is trick or treating. The best part of the night, in my opinion, is the special parades, and being able to ride the rides with minimal waits.
The weather when we were there was very warn - upper 80's, but you might want to bring a sweatshirt, in case the evenings are cooler.
Enjoy!