Another question for the brain trust. Is my ramp too low from the exit of the coop for them to be able to use? Does it need to sit flush with the “door”
No the ramp does not need to be flush with the door. They can hop up the extra few inches and into the door.
Siding/hinged windows might be nice for the option of letting in more air in hot weather, but you might get enough light from the vent holes up above, so use your best judgment on that - if it's dark inside the coop at/before sunset then yes you'll need a window or two.