In Extraordinary swimming, Terry also mentioned (I don't know the reference) that backing off the rotation is helpful. THat is where I got the idea.
As for the entry, I think I see it as more similar to free because I pay attention to the elbow in both strokes not the hand. In both strokes, the elbow and the shoulder enter the water almost simultaneously. You are correct that the hands are different. But to me, the focus on the elbow connection to the body is more useful than focusing on the hands.
As for the catch, again, there are obvious differences, but I try to think of them more as similar. In free, I try to maintain streamline from elbow to toes as my arm catches. In back I do the same. In back, the catch is out to the side for me, while in free it points more to the bottom, but concept is the same.
Terry has mentioned a lot lately that intention, somehow, can be more powerful than what is actually physically changing. This discussion may be about what we intend to do as much as what actually happens.
AS for tempo, cutting back on rotation cuts the distance my body parts have to travel in one cycle. It is the same in free. At slow tempos I can finish each pull at my thigh. At high tempos, I have to release just above my hip. I can do this without loss of stroke length. As I cut back on rotation in back stroke, I need less of the push phase to rotate my body so I can get my hand out of the water and recovering more easily. This gives me a more quiet and less rushed stroke which, I believe is more efficient overall. It feels the same as widening the tracks in free. Again, the main sacrifice of this for me is my pulling arm is never fully in front of my body which is a less powerful position. I am still working out how much rotation is best for me.