I have a 3 year old who never slept, has consitpation issues, and was exhibiting sensory processing issues... he is a complex child to say the least! It sounds to me like some of your son's issues are normal, some may be red flags. It's possible he likes older kids b/c he has an older brother- it's good you know how to ward off the things which set him off, like arriving early. My son had a very difficult time (still does) going into preschool with everyone already there, he would cling to me and get very oral with his tongue- it took him about 15 minutes to warm up, so he, too, does better with smaller groups at first. We had a full evaluation and there's a small chance he could end up on the autistic spectrum b/c of attention and fine motor but pysch thinks more likely possible non-verbal learning disorder (your son may have the same, it effects everything in their interaction, life etc. ) or that he will simply catch up- the full evaluation will be very helpful to you. Also, our son just had his adnoids out and ear tubes in. Our pedi had said we were going to see a world of difference in behaviour. While the surgery and recovery were awful, we are suddenly seeing drastic improvement- from sensory issues to behaviour, to focus. He will need some help with speech, but, knock on wood, for the first time in his life he's sleeping through the night. Anyway, I bring this up b/c our pedi mentioned a child she was seeing who they thought might be autisitc, he got the surgery and was 90 percent better- no sign of autism. It's worth having him checked out, particularly the adnoids (and possible sleep apena?) we went to children's for the slepe clinic and children's for ENT. good luck, thoughts are with you.