Actually, I would scratch the letter. When you write a letter to the school it needs to be all about facts and not contain any emotions. On the board I frequent (the spec ed advocacy board) there is an expert letter writer and she is soooo good I won a state complaint.
First you need to start fresh and have him retested. And you need to make sure he was tested in all areas of suspected disability. LIke for example my kids school kept on testing them with an OT that wasn't SID (sensory) certified. Of course the guy didn't qualify them for OT. Well I didn't know but IDEA says the assessor has to be credentialed and Sensory is one of them although it's not in the DSM 4. But here's the thing, If the child has a problem with sensory, and it is affecting his education, then he should qualify for services. They cannot dx, but they can determine if he needs services.
He does sound a bit ADHD and seems to have anxiety. ADHD is a OHI eligiblity and he would qualify for this.
Please start by telling your story over on this board...www.millermom.proboards.com. You will not regret it. They can help. Those people are just as friendly and helpful at this board.