New state, new challenges

I just moved to California and am a first grade Dual Immersion teacher here. My new school is amazing. Great leadership and great teachers. I have quite an interesting and definitely challenging group of kids this year. I will start with Mitchell.
Now this student is a biter, but does not bite other students- he just bites anyTHING that he can get his hands on. Throughout the first two weeks of school he gnawed at my table edge that sits near me in the front of the classroom. It looked like an animal with much sharper teeth than a child had gotten to my table. Mitchell sits right in the front of the rug area (which happens to be right next to my poor table) because in addition to his need for um.. oral stimulation... he also cannot sit still. He is a smart student, but has so much trouble focusing on the lessons because he needs a LOT of sensory stimulation.
During a lesson, Mitchell gnaws on my table (we have given him a chew toy so he leaves the table alone), licks the floor, table, and other students, chews on the carpet, rubs his forehead repeatedly against the carpet, eats (yes chews and swallows!) his shoelaces, pieces of paper, and his shirt (buttons included), hits the floor with his palms and feet, whips his head around in circles repeatedly and says it makes him dizzy, but it feels good.
One day, my sink was clogged and the sink became full of dirty water filled with dirt from kids' hands, paint residue, and spit from kids drinking from the water fountain which is also over the sink. At the end of the day, Mark gets up to walk around (he now sits behind the rug on a chair and has a signal that he uses when he cannot sit anymore. He gets up and does a walking lap around the classroom, drinks water if he needs it and sits again). He decides to get a drink and instead of using the water fountain, he sticks his face in the dirty sink water and starts to slurp loudly! I was in the middle of teaching a lesson and had to jump up and yell for him to stop. He looked up at me startled, and then said, "I'm thirsty. It tastes good." He then stuck his head back into the sink water and began to drink again. I had to get up and explain to him (again) how dirty the water was and why it was bad to drink from there.

His mom comes in and sits with him twice during the week during the morning to help him focus. I need some new ideas on how to help this kid! The signal thing works sometimes. Other times, he abuses it and ends up trying to make the students laugh with what he does (i.e. doing pushups while doing his lap around the classroom). He has low self esteem and feels like he needs to be the clown for others to like him. I made him one of my Behavior Monitors so that he has to be the leader in good behavior. He has the power to at the end of the day choose someone in the class who had great behavior. He needs to make sure he sets a good example, otherwise, he loses this job for the day. It has also helped him, but the thing is, he can't control what he does. He's allowed to chew on his chew toy and build, break down, and build again dry-erase erasers while on the rug and while he's supposed to be listening. Yet, he abuses that too and bothers other students still. How else can I help him focus? Any ideas?