Smaller combs & wattles reduce frostbite risk, but adequate shelter is essential. Need to consider perching toes getting cold too, small perches like we see parrots on aren't good, I actually used 2x4s.
Once chickens know & love their coop, feeling safe & secure inside it, they'll often get closer to the coop as daylight begins to fade, then put themselves to bed when it's dusk. Calling them in sooner mid day (like if a bad storm is approaching) isn't always easy, but if you practice with treats (mealworms) in addition to a sound (the bell, or I call mine in same way, same tone & same words) they'll learn to come to you Whenever you need them to, not just at dusk. This can be fun to teach & create bonds with your flock, but it's really also a very valuable life saving action at times. When we had sudden storm bursts, I was so glad my chickens listened to me & I got them all in, then got myself inside safely, Before hail, tornado or lightning bolts started! Trust me, it's not fun running around outside with lightning bolts zigzagging across the sky. Get yourself 2 good weather apps on your phone, too, set alerts so you know what is headed your way. Work with them & teach them to come running when you need them to...Before a storm actually hits. Unfortunately we cannot be with them 24/7 due to work, school, & life as such it is, but at least if you practice this at times, the chickens will learn quickly & feel when the barometric pressure changes & get themselves to safety. They really are pretty smart...most of the time.
If they're out free ranging & a fox runs up or hawks dives in, they'll scatter to run & hide, some will run for the coop if nearby, some may run to hide under the nearest shrub or elevated shed. Depending upon your types of predators, the predators lack of fear of humans (some will not care if a human is right there & still grab a chicken dinner), the abundance, or lack of, places available for chickens to hide, you may rethink the predator proof pens idea & only free range if you're right there with them...I only mention it because that's what I had to do, to keep my flock alive.
As for breeds, I have Wyandotte, Maran, Australorp, EEs, Buff Orpingtons, Barred Rock, RIR & I haven't had any issues, but I did insulate the coops, they naturally stay warmer in winter, cooler in summer, plus I have fans & windows on all 4 sides, mostly open, unless we get storms, then I just close the windows in the direction the wind could blow precipitation in. The goal is to keep coop dry. I scoop poop under perches daily, only takes 15 min & well worth it, for the times when they'll have to stay cooped up due to a week of nasty weather, (if you scooped poop all week, then those days cooped up, poop accumulating, won't be so piled up than if you hadn't scooped). Piled up poop creates it's own humidity...makes coop "wet" even if you don't have outside precipitation blowing in, so always strive for a dry coop. Simple humidity can cause frostbite, too. For those bad weather weeks & months, they'll be inside more, so consider the size of coop & perch space, more is better, less squabbles. A dry coop is a healthy coop, I use wood chips inside coop, big bark chips in pens. Covered pens are best, but mine are only covered by hardware cloth wire. Try to avoid muddy areas, add more bark mulch. I check for bumblefoot & address it immediately. Know that a wet coop or muddy run can cause bumblefoot.
Predators in general will go for any chicken they can catch, but white & lighter color feathers seem to make chickens easier targets, easier to spot, even if they hide under shrubs. Cooper Hawks zoom right into shrubs full speed...they catch sparrows easily & can tangle with chickens, too. I noticed they always go after my paler feather color chickens & pigeons. If all you have are dark color feathered birds, they'll still go for them, though. They gotta eat, too, just make it harder for them to eat your flock.
Hope this helps & best of luck on your chicken journey...You're gonna love it!
