Your school professionals concluded that your son has learning disabilities and ADHD. He will need special education services along with the general education programs.
My first question: Who diagnosed him with an auditory processing disorder? This person should be advising you. Such a disorder often causes learning disabilities. Was he evaluated for this?
If your son does not have ADHD, he should not be considered for an ADHD medication. I cannot answer your questions on placement in middle school without knowing more details.