That is why I got the digital scale rather than the Incredible Egg scale. It doesn't have the needed range. How do you know that your girl laid a 114g egg if anything over 71g is OFF the scale? And how about the TINY 4g egg I got some weeks back or the 16g egg 2 days ago?
Yes, my girls all started with pullet eggs that got bigger as the girls got bigger. That can easily take 3-4 months.
Given your climate, I would make sure that coop has a TON of ventilation. Otherwise it will be roast chicken, they can't take off their down coats. And create out of the coop shade spots, my girls spend ALL their time in the shade other than early and late in the day.
Depends on where it is hotter I think. If it is cooler in the new big coop than it is out in the run, yes they will go in the coop. My coop is a converted horse stall in an old barn so they have all day indoor shade if they want it. Thus, they never go in the coop during the day except to lay or eat chicken feed. They either hang in the indoor run or in some shady spot outside the barn.
Looks like you did a lot of work, but I think I see a ventilation problem. The window is right in front of the roost. No way to get air moving through the coop without it blowing on the birds.
And I know a lot of work went into building those steps to the roost but don't be surprised to find them covered with poop. Chickens are really good at pooping, wherever they happen to be when the urge strikes.
BTW:
https://www.backyardchickens.com/t/956958/mama-heating-pad-in-the-brooder-picture-heavy-update
Far better way to raise the chicks than a 24x7 heat lamp.
If they have other chicks to play with, not sure why they would care about a mirror. Then again, my girls don't have a mirror so I don't know if they would look in it or not.