Please post photos of that coop inside and out plus measurements in feet.  Or provide a link that shows that.  It's easier to talk about something when you have an idea what it looks like.  The main things I'll be looking at is whether there is a roof overhang, height of roosts inside the coop, materials used for construction, location of those gable vents, whether it is elevated, and just general configuration.  After all this discussion what specific topics do you want addressed?  I'd guess lighting, ventilation, and number of chickens?  A little bit about your goals or why you want chickens might help.  You've already said you will want to integrate more chickens later.
I agree with most of the comments about typical prefab coops but let's see what you are dealing with and what you can do instead of assuming.  There is a pretty good chance you will need to make modifications.  Lots of people use prefab coops but not always as they are advertised.
I do not believe in all those magic number thrown out for everything to do with chickens, whether that is square feet per chicken in the coop or run, ratio of hens to roosters, length of roost space, or square feet of ventilation per chicken.  There are way too many variables in climate, how we manage them, flock make-up, and so many other things that one number doesn't cover every chicken coop on the planet.  
I want to emphasize what Aart said, it can help us if you modify your profile to show your general location.  That's for a lot of things other than just climate.  You mentioned Massachusetts in a post but that's pretty well hidden.  If you put it in your profile it is always available.  
As for ventilation, your requirements will be different form someone in Perth, Australia or Fairbanks, Alaska.  Your requirements will be different in summer versus winter.  What are you working with?