Yeah, small snakes and chickens don't bode well for the snake at all. Chickens love their protein. Watched one of my rocks consume about a one foot snake lickety split after the fight where that snake was stretched from here to Sunday.
Same girls chased a 6 foot Coach Whip all around the yard...
I'm zoned agriculture and with 5 acres, unlimited number. For now I have 26 Barred Rocks. Not too sure about the coop but that is a fight for the future.
Once on the roost with lights out, they stay there until sunup or lights on. Something you might want to try is to check their crops before they go down. It should be full and feel like a large knot. That means they have filled up for the night. Come daybreak, they will fill up again.
To much moisture and still air. You can try using a small fan to keep air moving around them. You can also spray with hydrogen peroxide, not harmful to you but really slows mold down. I would also suggest that you go to some of the sprouting sites. They have great info on sprouting.
You think green grass is good. Get them a head of lettuce and watch them tear it up. I have 26 Plymouth Rocks and I gave them a leftover head about 4" in diameter in their fourth week. It was gone within 5 hours, stem and all.
I started with the fine but switched to flake, less dust. It doesn't seem to matter which, they eat the small bits. Doesn't seem to matter they are growing just fine. Just make sure they have some chick grit.