S.L.
You have several things going on all at once and I believe in a way it's all connected. To start with, the boy doesn't feel that great. I live with acid reflux and know that it's a mixed bag of lots of symptoms. The best thing you can do there is work hard on keeping his diet healthy, offering an all day healthy grazing of food without letting him eat a large amount of something he may like. It's tempting to let him have as much of something he wants because of all the times he doesn't eat much. But eating too little or too much aggrivates acid reflux.
For the behavior, you need to find a safe place for him to be. I suggest a pack and play. Even if he can climb out, then you'll have to stand next to it and put him back in even if it's 200 times. Eventually, he'll figure out that when he hits he goes in the pack and play. When he screams at you or pulls hair, he goes in the pack and play. At his age it's not about a timed amount of time as in time out. It's really about getting him away from people so that he can not hurt anyone. Keep the pack and play near enough to not make him feel absolutely isolated. But far enough that sooner or later he'll get tired of being separated from you and whoever else is around. You need to be consistent. You can not make any excuses PERIOD. If it bothers you to leave him in there and you wonder too much about how long to put him in there, make a deal with yourself. Every time you put him in there clean out a drawer, sweep a floor, clean off a counter etc. Just think...every time he gets into trouble you will do some small cleaning project and eventually your house will be VERY clean.
This really will work if you do it faithfully. He'll learn that you are not reacting in an emotional way. Kids feed off of emotions. The more emotional you are, the bigger the pay off they are getting. Also, he'll not have the run of the house.
The final thing you need to work on is just as important as his eating and how to handle the naughty behavior. You NEED to find an outlet that will make him tired. You can buy a very small moonwalk for around 200 that will fit in most living rooms if you can move back all the furniture. You can get him a blow up ball pit. You can get a small trampoline, the personal exercise kind or one for kids, and help him jump on it. You MUST find a very physical outlet for this boy. You can get some buckets, the small 3 gallon cleaning kind with handles. Fill them with wooden blocks, cars, and any other toy that will make them a little heavy. Teach him to carry them from place to place. Give him play dough and teach him to pound it. You need to tire this boy out!
If you will spend a little time and money to change the way you deal with him, you'll have a new boy in no time.
I didn't talk about sleep patters because his sleep problems are a symptom of the other things. He isn't feeling well, isn't getting the right kind of dicipline, and he isn't being challenged physically. The sleep will take care of itself when you handle these things.
Suzi