First
As long as your coop is vented but not drafty your birds should be ok. Lights are a personal preference. I have 3 watt lights in each of my coops. I also have electric wire around my coops and pens to keep out predators. If I can see the lights on at night then I know my electric fence is working. It's been quite a few years since I lost a bird to a predator. I also have good heavy duty netting over all of my pens. I had an owl kill some of my birds so I put up the netting. I couldn't figure out how something was getting in so I put up my game cameras and saw the owl on video. I have heard critters touch the electric wire (probably coyotes). Once they touch it they don't come back to test it out again.
