Hello Sessie! Welcome to the forum and to the world of chicken keeping. I'd like to address all of your questions but don't have much time, so I'll talk about weather proofing your coop.
Frost bite is very hard to prevent on large single comb breeds like Marans. I live in Louisiana and applied vaseline to my Japanese bantams' combs and they still got a little frost bit this winter. It doesn't say anything about neglect or mistreatment. Chicken coops don't need insulation or heating. You want there to be adequate air flow so that there isn't a build up of humidity. The humidity is what's dangerous for a chicken. They can handle cold temperatures very well as long as they stay dry. So you want to figure out if you have air flow in your coop and make sure it won't become moist and humid when your flock decides to roost for the night. Secure gaps where the walls meet the ceiling help to funnel moist air out.
There isn't anything I know of you can do for a comb that is already damaged. Maybe someone else has some insight. Depending on the severity of it, I can't imagine you getting more than one or two points deducted at a show for it. I believe it is judged under conditioning.
I'd love to see photos of your new guy and your coop. We could give better advice on your cockbird and maybe some improvements to the coop and run.