Grinchmas is all day in IOA with about 5-6 shows a day. Plus Suess Landing is decorated the whole time. Then the Macy's parade is in US around 7-8 at night at park closing. So you should have no problem doing both and rides durring your visit as long as you have a 2 park multi pass to allow you to visit 2 parks onthe same day.
Also, it usually starts right around the first or second full week of December.Depends on when Tgiving is, and how fast they can get it shipped here and everyone trained.
Sorry about the hours, I didn't even check. I remember last year that it was dark by the time the parade finished. Anyways, we will be there also Dec 3-6.