Unfortunately, I have no advice, but just want to tell you, please hang in there, you're not alone. I have a 28-month-old son, and "hell" does not quite describe what I am going through with him. He is intense. He doesn't cry, he shrieks. I avoid going places with him for fear he will pitch one of his frequent tantrums. The problem is compounded by the fact that he is very big and strong. It took 3 nurses and myself holding him to get his shots at 2 years. When it's time to leave, say, the park, he starts shrieking and bucking like a bronco and I can hardly subdue him to put him in the stroller. He also doesn't talk even though he can. But he prefers to let his needs known by other, much more obnoxious means. I love him more than anything, of course, he is my little star, but his temperament makes my parenting experience pure hell. Sometimes I just have to leave the room to have some time away from him and then I fill guilty! I feel very unhappy and depressed at times and also sometimes I think I am doing something wrong. Just know that I feel your pain and wish you all the very best!!!
Rest assured, this is all normal behavior. If your child has a higher IQ than the normal child, the behavior is worse. Smart children misbehave more, because they have very active minds. As far as the hitting and such, 2-year-old do not think "what will happen if I do this". 2-year-old think "I should do this" and they do it. Reaction without thinking. That is why so many 2-year-olds will push siblings down the stairs. They are not thinking that they will hurt the sibling; they are thinking "pushing will get them out of my way". The best way to handle a tantrum is to let him throw it. He feels stressed and needs to throw a tantrum. Let him. Do not give him attention for it and do not become concerned (which is another form of attention from you). The child psychologist and psychiatrists that I worked for said that "anything goes with behavior until the child is 3-years-old". Once he is 3, he should settle down more. You need to stay in control, parent, and do not seem concerned or worried about his behavior. Children pick up on every emotion of the parent and they will act upon it. If the parent is sick, the children will be out of control, because they can and the parent cannot parent at that time. If the parent is emotional or stressed, the child will have bad behavior and be wild. The more stressed the parent becomes, the wilder the child becomes. Calm, secure, and lots of patience will get you through the 2's.