Beautiful coop. I'll respond mainly so I can see those inside photos.
But a bit of trivia. They do stand up when they lay the egg, but it's not very high. The egg and poop both come out of the same vent. Both the digestive tract and their internal egg making factory are connected there. But to protect the egg from coming into contact with the poop when the egg is laid, a small portion of the egg making factory actually exists the vent a bit. Not much but a bit. To prevent trash or bedding from getting stuck to that exposed bit they stand up high enough to keep it clear of bedding.
But a bit of trivia. They do stand up when they lay the egg, but it's not very high. The egg and poop both come out of the same vent. Both the digestive tract and their internal egg making factory are connected there. But to protect the egg from coming into contact with the poop when the egg is laid, a small portion of the egg making factory actually exists the vent a bit. Not much but a bit. To prevent trash or bedding from getting stuck to that exposed bit they stand up high enough to keep it clear of bedding.