My ds 11 has some of these characteristics, slightly I would say, maybe. In our last parent teacher meeting 2 of the teacher says when they are working quietly in class on their work he makes noises or something they couldn't really describe what it was maybe singing. They said he gets quiet when they tell him. It got me thinking a bit. He is always singing, especially when he is doing homework. He sings the formulas to math. He will sing the questions to everything. It is nothing to worry about but this did get me thinking. He is in a new school this year so I chalked it up to him dealing with that. He does have a ton of homework for a 5th grader and this year has been more then he ever had at the public school in grades 1st - 4th.