I didn't read all the post so I hope I'm not repeating but....

Some thoughts on finding playmates. I think it will get easier as he gets older. I think it's common for smart kids to find each other.

I would try to get out and do activities like nature classes, science centers, Museums and Lego classes. This is where I have been very surprised at how smart kids seem to be. Some of the better classes attract others who are looking for stimulation.

Best of luck to finding some good playmates.