In November you have the 1st and the 11th which are public holidays and there are school holidays in all 3 zones until the 8th
Starting from the 12th it will be great as you'll have less people and all the Christmas stuff.
EMH are all year round afaik , traditionally there are only fireworks on the bonfire weekend but with the Dreams spectacle and the 20th who knows what will be going on then as night entertainment nor until what times the park will be open to.
Here are last years hours showing EMH and opening times
http://www.dlrpmagic.com/calendar/monthly-park-hours/2011/11/
Weather can be cold but not freezing,we don't normally get snow until the end of November/start of December at the earliest.