First, and most importantly, there is nothing you can do at this age to fix what your son is doing in school (except seek professional help). I say this because to change behavior the consequences must be immediate and consistent. Anything you do at home, hours after the fact, will not have an effect at this age. This is something that the school needs to deal with.
But the real question is why is this going on? You said that last week you got 4 phone calls from the school. Up till this point, were things basically ok? If so, then something has changed either at school or at home to cause this - and typically its at school. If this has been a problem all year at school, then they have finally decided to get your attention to get help.
He does have a few of the symptoms of being hyperactive. Perhaps you would like to take a look at this link and see if this does describe some of his other problems.
The link is -- http://helpguide.org/mental/adhd_add_signs_symptoms.htm
I am also the CL on the ADHD forum -
http://www.medhelp.org/forums/ADD---ADHD/show/175
please feel free to post to me there if the above link makes you want more information.