It may start with lower crowds, but with Thanksgiving right after you leave that week will have higher attendance. Many schools are out all of Thanksgiving week, and crowds start to build the weekend before Thanksgiving.
The Christmas decorations will be up as the MVMCP will have already started, first party is on November 8.
As far as cold goes, it varies. Once I went in mid November for a week, at beginning it was in low 80's and we were swimming, then a front came through and I was running out to get jackets and gloves.