1. Built ours by hand. We are handy and like building stuff and enjoyed the process (mostly). We also could take our time because we built the coop/run BEFORE we got the chicks. You are limited in buying pre-made or a kit as far as what is available. If you build yourself, the sky's the limit. We designed ours off a few different small/medium sized coops here on BYC Coop pages.
2. Floor of the coop. Well, that depends. Mine is covered in linoleum, and then 3-4 inches of pine shavings. I have a poop board under their roost filled with Stall-dri (works like kitty litter) for easy cleaning. Their original run is covered and attached to the coop and has about 1 ton of builders sand in it. Awesome stuff. Great drainage and easy to rake clean - and the poop I miss somehow disappears into the sand. I've also expanded their run to an outdoor uncovered area. It just has dirt. The girls pecked it clean of anything green or growing within 2 weeks. They spend most of their time out there and love digging huge holes in the dirt for dustbathing.