Great advice above, nothing to add to it, and not enough knowledge of MA weather to offer much guidance.
Instead, I'll emphasize three points.
1) Abundance is a social lubricant. The more space you can provide your birds, the better they will tend to behave, and the more flexibility you will have in managing your flock.
2) Weather Sheltered 24/7/365 ventilation which doesn't cause drafts on your birds is probably the most important feature of a coop in low predator environments, and the second most important feature in high predator environments. The most common modification around here - even to prefabs and kits - is ventillation improvements.
3) Coops you can stand up in are easier. Easier to clean, easier to maintain, easier to repair, easier to ensure draft free, weather sheltered ventilation. Easier to find off the shelf options for modifications and improvements at the home store.