Yes to both. Even though lines may be shorter, it is still faster using a FP. You may want to alter what times you choose. If you go at rope drop, you could get FPs for later in the day when crowds build a bit. If there are some dining experiences you want to to have, go ahead and get an ADR. You don't have to be obsessive about it though if you want to be more spontaneous.
Yes, get your three fastpasses for sure. If you don’t care where you eat you can always find someplace last minute as long as you don’t have a must do restaurant in mind. Many say there are no more really slow times at Disney World.