What Pat said.
That really is smaller than optimum for that many birds. Assuming they are common breeds, both the run and the coop are small.
This doesnt mean you cant do it, it means you will be get to experience the joys of overcrowding and chicken poo. Waste management and disease control will become your biggest concern. But dont worry, you're in good company. Most people have the same issues.
You most certainly can insulate and that is wise. Your goal is to eliminate subfreezing temps from their living quarters - you dont need to make a sauna out of it.
As far as ventilation is concerned, decide what you think is best and add 50% more area. Chickens have high metabolisms and suffer when kept closely, without adequate ventilation.
Combined with overcrowding, this can spell trouble. Most commonly this results in respiratory ailments, to which chickens are rather susceptible.