My son also receives therapy at Arlington Pediatric Therapies. It's just off of 53 between Rand and Dundee Roads, and they have been terrific. My son also just turned 3 and will start receiving services from the school district after Labor Day as well. Many of the parents I have met through this whole process have their children doing public and private therapy, especially if insurance pays for it.
As for school districts, you may really need to be a pest. I am a teacher in one district, but I live in a very small district, and calling the central administration building speical ed person really turned me off. They gave me no helpful info, and there was no publicly accessible info about the services and programs, etc. until I found the district special ed parent group. They really came through for me, and gave me tips and contacts to get my son evaluated and qualified. I've sat through many IEP meetings for students in multiple districts, and you need to know that YOU need to be the expert and the driving force for your son when it comes to securing public school services for him. Good luck.