Nice craftsmanship! Are you sure you're not a carpenter?!
The only thing I'd point out is that you may live to regret putting the chicken door in the floor. I think you may find that whatever bedding you put down on the floor of your coop ends up falling out that door frequently. You can put a low lip around the door hole to mitigate this problem somewhat.
I cut the popdoor in the side of my first coop too low and suffered a similar problem....that's how I know.
Are you planning to add hardware cloth vents on the tops of your walls? Looks like you'll have plenty of ventilation if you do.