This is significant because us people and dogs do things over and over again to learn and be taught. It is important for us to learn things that we would eventually use in our daily lives. Having a dog means you're going to have to train it, and that takes time and skill because you're teaching them how to do things they aren't use to. So you do it over and over until they get it.
This is significant because Enzo wants to die to become a man in his new life. I think that he is ready to die because he served his time here on Earth and he is getting old, no longer able to pick himself up. So if he dies and becomes a man he will have a new life being able to speak out and be heard.
This is significant because if your eyes are looking somewhere else like your phone then you will most likely crash or something terrible will happen. But it could also mean to keep in control of the wheel because if you let go your life will be a mess and so will that wreck. For Denny he has to pay attention to the track or he will end up injured or in a wreck.