That wire is kinda large. You'd be surprised what predators can get thru that. Might want to consider some 1/2 inch hardware cloth. What did you make the boxes out of? The chickies are cute. :)
Sorry I didnt have time to read everyone else's posts...chicken wire will keep the chickens in but hardware cloth will keep predators out. It's worth the cost..trust me!
We use hay. All the waste goes into a 5 gal bucket until the bucket is full. Sometimes people with gardens ask for it. Otherwise, we fill the bucket with water and let it "cook" for a few hours. Then water the flowers, trees, whatever. Like the others have said, the material (hay, pine shavings)...
We have some chickens who fight over nest boxes and one who will let it drop where ever she happens to be. You just never know what they're going to like.
About the roosting tho...in all the different coops I've looked at and taking into account the things we've tried...I think they like...