I would also encourage you to enroll in parenting classes (for parents of children with ADD if available) to learn the tricks of the trade from others who have experienced these kind of problems. If parenting classes aren't available, look for books on the subject at the public library.
As the school year progresses, continue to evaluate and work with your son's teachers and counselors to determine if his placement level is appropriate. Many times children just need time and the opportunity to succeed in a challenging situation in order to know that they really do have control and power over their own learning.