Sweet PDZ is a horse stall refresher- it absorbs moisture and smell. I forget exactly what it is made of but it is completely safe for chickens- I think it is made from a mineral maybe? Works GREAT for chicken poop. When my girls are getting on the perches at night they kick a little on to the floor and freshen up the shavings too.
Here is the outside of the coop (can't take credit for the design, it is a Amish kit we brought)
I LOVE your coop! I've looked at it on the Little Cottage Co website and I see that the chicken door is on the front next to the human door...that's not ideal for me and I noticed that your chicken door must be on the side. Was changing the placement of the chicken door something you did yourself or an option they have?