Hello! I'm brand new to the forum and chicken keeping, though not new to livestock and pet management (so far chickens have proved to be a combination of both). I'm trying to make some decisions based on information I've read across the internet, and I'd love some perspective from experienced chicken people. I have a sturdy chicken house with a poured concrete floor and windows on the East side. The main coop area is about 12'x12' with a brooder/hospital area in the front (about 4'x5') and a foyer where we keep metal bins of supplies (so the whole front area is maybe 12'x4'). The covered chicken yard measures 35'x35'. I currently have one year old rooster, his 4 EE year old girls (who are laying spectacularly), and 4 Silver laced wyandottes (who were sent into a stress molt after their move to our property 3 weeks ago and are only now starting to become red-combed again). I also purchased 7 3 month old Black Java pullets that currently have the run of the brooder and foyer area. They were someone's 4-H culls and they're really nice....and huge. So question 1) I read a while back that a certain density of birds is needed to maintain warmth in cold climates. I live in an area that will see sub zero temps for weeks at a time in winter. I do have electricity out to the coop. Do I really need a critical mass of chickens? I'd like to expand the flock with day old chicks but I'm not sure if I should do that this summer or next spring when I'm a more experienced chicken handler. 2) What is the maximum number of birds that would be happy in this set-up? The 1.5 sqft per bird rule says ~40, but that seems like a LOT of chickens for that space! 3) How do I introduce the Black Javas into the flock? Should I leave the door to the main coop open so they can mingle? Or should I shuffle the youngsters into the yard and hope they follow the other hens back inside to the main coop? 4) I was against having a rooster, but he's actually pretty handy. He tries new foods first and let's the girls know they're tasty AND he showed the hens how to go in and out from the coop into the yard. However, two of the EEs have significant feather breakage on their backs and I'm worried about their ability to stay warm in the winter. Will adding the Black Javas reduce the roo's attention to his favorite hens enough to let their feathers grow back? I'm super open to any suggestions. I don't know anyone else who keeps chickens! Thanks!