One suggestion: For your "failed" attempt at growing grass, you can build a 2x4 frame and staple wire to that, so the grass is always 3.5 inches long, and the chickens can't eat it right to the dirt.
Nice coop! Someone could easily make a coop with these instructions!
One suggestion: Overhangs on the front and back are always a good idea. When the roof ends are flush with the building, there is a much higher chance of water getting in.
When insulation is squished from tucking it in place, it loses some of its protection from cold/heat.
I made my windows opening by making a frame with hardware mesh and nailing it in place, and then I glued plexiglass to another frame with hinges and a latch. It stays open most of the time, but on stormy days I close it to be safe.