I'll only address the first question. Let me clarify my original post. If you are talking about CC onboard an aircraft, forget it. Unless you are a sky marshal it is not going to happen. PERIOD. You will probably be arrested if you attempt to do so. If you are talking about checked baggage, check with the airline. The policies vary from carrier to carrier. Delta just changed their procedures.

As to the rest, I will let those more familiar with IL laws comment. My only observation is this. You stated you had done some research. Even a cursory search should have revealed some of the misguided attempts to carry a weapon in Chicago. I personally would never attempt to do it. I don't think it is worth the risk.