Welcome...

and our Illinois thread.
Insulation is not as important as a draft free coop. Ventilation is most important. Ventilation (definition) means free air movement that removes moisture and ammonia from coop interior, but does not cause draft action that would ruffle chickens' feathers. Insulation such as you describe can also be bad, in such that chickens may pick on it as well as eat it.(don't think that would be Ideal.) If it is sandwiched between plywood, then chickens would not have access to eating it. Insulation not properly protected, can harbor moisture and mold.
MAIN thing is PROPER VENTILATION.. There are many articles here on BYC about that subject. You can ask any specific question here also.
What breed of chickens do you have? If they are the COLD HARDY VARIETY.. than you should be fine. Even with the best efforts sometimes chickens do encounter frostbite on their wattles and combs. They will recover on their own in due time.
Some peeps do add heat to their coops. Problem with this is multifaceted.
1. Makes chickens dependent on the heat and do not grow enough own down. Have a power outage long enough and your chickens suffer.
2. Can lead to premature molt in winter, which is anything but good.
3. Expensive utility.