@broadwing, I was just wondering, your 10 year old has lived such a long time ...what have you been feeding her and to what else do you attribute this longevity?
Once they are feathered, they can handle your winter weather.
Integrating can be done using the 'see but don't touch' setup. Temporxrily divide coop and run. Monitor reaction from hen over a week or two.
Re the rats, yes gotta do something. I never leave feed out at night. I kept setting traps...