Regarding the Halloween Parties, while they have not yet announced the dates or any details, it's worth noting for the last several years almost all of the parties have sold out ahead of time. So if you are there on Halloween night (when there has historically been a party), tickets will probably sell out well in advance (there might be a few day of tickets, mostly for on-site hotel guests).
As others have said, Gay Days weekend is November 4 and 5, which is expected to bring in pretty good sized crowds. There might be also some attraction closures as holiday overlays are installed (Jungle Cruise and IaSW most likely) or removed (Space went down 11/1-2 last year to remove the SMGG overlay); this all assumes they do the overlays this year and follow a similar schedule to last year.