We had friends at went to DC at Christmas last year, it was cool but fine. Oct should be great!
Can't help you with crowds at US and IoA but, WDW is okay at this time of year. This will be our first trip to US/IoA - finally the kids are both tall enough to enjoy US/IoA.
88 - FW
92 - Offsite (Holiday Inn Main Gate East)
93 - Dixie Landings
96 - CBR
97 - All Star Sports (Basketball)
98 - All Star Sports (Surfing)
99 - Disneyland!!!
99 - All Star Music (Calypso)
00 - All Star Movies (Love Bug)
01 - All Star Music (Calypso again?)