I can certainly understand your stress levels about this situation. As an aside, you may want to edit out your son's name (replace it with DS) and also the school/university names... just in the interest of privacy.
Will the counselor be working with your son on coping techniques and on sorting out his feelings more appropriately? If so, that could be very helpful.
This is a very outside view, but as I read your post, I can see some reasons your son might be reacting as he is at the moment. Time may indeed help, if the school can work with him through the adjustment. Last year, he was at the top of the class, and with no effort. But, he also experienced school as a place that led to punishment for his behavior and ultimately, a place he escaped. Now, he is in a new school, it seems he has to work harder but he doesn't know what that means, necessarily. He's not really used to doing so and may even worry that it means something is wrong with him. So he is confused and acts out.
There may be complicating factors, for example, the school may be more strict (although it sounds as though the prior one is as well).
