We have a Olive egger/Columbian Wyondotte on 13 eggs. Two are pure Flower Hen. The others are half Easter Egger, Turkin, Java, Rhode Island Red, lol. Oh, and Welsummer!
We rehomed 4 roos so far. Our chickens are very dear to us and once they got with their own hens they were happy and content. This is Lucy at his new home.
I think your coop is great for 3 hens.
Put the food and water where they will not poop into it roosting and out of the rain and so they can still get though the doors and jump up to the roots.
I would let them out in a little temporary chicken wire pen supervised.
And then let them out, they...
My chickens get little bit of whole corn and meal worms. Layina oyster shell probiotics natural American grown crumbles. Purina grit.
Chopped kale today. Greens everyday. And sometimes apples, oatmeal when it is cold and raining.
Austin Texas is also very dry but under the trees if there is feed on the ground for a long time I get white fuzzy mold.
I dig in up and throw it in the compost pile.