Hi, there! My family has gone to WDW the last few times the 1st & 2nd weeks of February and there have never been crowds--it was great! At EPCOT and the Magic Kingdom we were allowed to stay on rides like Test Track & Big Thunder Mountain and go around and around as many times as we liked without disembarking!!! The kids loved it!! FastPass was not necessary! At the Animal Kingdom we did grab a FastPass at the Kilimanjaro Safari and then got in the regular line--took less than 10 minutes to get on the ride!! When we got off it was our FastPass time and just walked on and took the ride again!!
We love this time of year in Florida and are going back on the 9th of February--highly recommend this time of year (we're coming from Maine where it's well, well, well below zero and even if it's in the 60s in Florida is a tropical paradise for us!!! (February 2004 the weather was in the 80s!!!) We totally lucked out!
Hope this info helps with your decision!!