HMMMMM what to do with the crate?
OHHHHHHH the possibilities.....
If you can get the top off in one piece you could easily lift one side to slant it before roofing goes on to help shed snow and rain. You could then add hardware cloth along the raised edge under the roof lip for vents.
I would put it on 2 foot legs so the mice stay out and the chickens can go under. It would also make it easier to clean.
I would hinge the end you have off for ease of cleaning.
You have plans for windows already so that works.
Paint it to match your home or give it a funky look if that suits your tastes better.
Nest box off the side so you can access it easily and the floor space is not lost.
I hung a smallish feeder on the inside of my clean out door on my small coop to help keep the floor area clear too.
It would be pretty easy to give it a peaked roof and make it look like a cottage too.
Great find....... I am off to search craigs list now for perhaps a find of my own....... Oh the things one can do with found items.....