Hello and welcome to BYC! Glad you joined.
Insulating the tin roof might not be a bad idea. They tend to sweat in the winter even with excellent ventilation. Amish built coops are well built but not well designed for high ventilation.
Hello and welcome to BYC, You found an Amazing Poultry Community to be a part of with many great knowledgeable members who are more then willing to jump in and help you along your journey with any questions you may have.