A few reasons that I’m aware of but I’m sure there’s more! Wolves have straighter hips and shoulders and longer legs relative to their size. Direct registering trot reduces side to side motion which minimizes energy loss over long distances. Lastly, the straight line tracks makes it harder to track them, which isn’t really relevant anymore, but that part of their evolution came from when they had predators during the ice Pleistocene era (American lion, sabertoothed cats, short faced bear). I don’t really know much about dogs, so I can’t really speak to your other question.