I'm hoping that you'll get more feedback! Try also reading through the Forum specific to Coop building. This coop on BYC has gotten a lot of recent attention. It's pretty sweet. I really like having separate rooms and your space looks perfectly laid out for that already. It's SO beneficial to me...
Wow! Lucky You! You are so talking my language, renovating what's already there, love it! I even love your dog, haha. :welcome Welcome to BYC! You're right, this is the right place, nothing compares. You're going to get great advice but I'll just throw a few cents in there. Spend time reading...