You will never be happy with just 4 birds! They are worse than potato chips! Go bigger! Trust us all in that little gem!
Oh, and up here in NH, if you can build on a little area for you to get in and out without letting out thier heat on chilly days, you will be so grateful! We converted an old shed, 2/3 for the chickens, insulated and seperate, 1/3 for me and my supplies, feed tubs etc. On snowy cold days, I go in thru my door, and they stay in and rumage around on the floor. They have thier own door out, but they dont like the deep snow much.
Think big, and settle smaller!