permanent coop or tractor for 6 birds

[Kelson]

We just picked up 6 birds last Sunday. 2 are only about a week old the others are between 5-6.5 week's old. I currently have the older birds in a temporary tractor during the day and bring them in at night. We are going to get started on building something better this weekend. The original plan was to only get 3 hens and have a tractor with built on coop. We couldn't resist the cuteness and now have to draw up new plans for them. We are in Virginia so we do get some snow. This past winter we got two 5+in storms and several dustings. Hubby still really wants to do a tractor, as he likes the idea of fertilizing the yard, no mucking out the run etc. We have an old shed that I think would be a great size to turn into a permanent large coop for them.
I just worry about smell, and of course extra cleaning. So ideas, suggestions, pictures. All would be appreciated!