Re: frostbite: vaseline used as a PREVENTATIVE also is excellent! Try it yourself; go out on a frigid windy day, especially if there is sleet--vaseline one cheek. You'll see the difference. The barrier keeps the tissue from losing water, and the humidity from damaging the surface cell layers. Do apply vaseline to frostbitten areas to protect, but avoid rubbing; it's very painful; I've had MILD frostbite on the face from sleet, and it burns for days, even though nothing apparent but what looked like hives.
Re: treatment: suggest reading up on human medical sites (Mayo clinic, etc.--reputable ones!) on google, to see what they are doing now--frostbite care tends to change over the years with increased info.
Re: pain: Agree that chickens hold still to not attract attention. Some point to chickens eating during surgery, but they are also programed by nature to never pass up food, so that may not tell--that could also be stress relief. We have LONG known that human babies shut down after (and often during) circumcision, and that was in the past (and still by more ignorant and/or callous medical professionals) pointed to as "no pain", but monitoring devices long ago demonstrated the opposite; the emotional withdrawl is a RESULT of suffering, and the pain is acutely felt, notwithstanding a partially incomplete neurological system.
Re: straw--very bad for bedding for animals, because of moisture and compaction. Shavings better, maybe DRY sand if shavings too costly?
I have only pet bantams, and have a small (space restrictions) coop for them, so I have a raised 3 x 6 (floorspace) cage attached to the coop, with a small pop-hole open into it at all times. Two Plexiglass sides for visibility and light, choroplast back panel (inexpensive) with vent, and choroplast roof (again, inexpensive, lightweight, and easy to work work with--only a box knife and tape required!) that is slightly lifted for ventilation. Insulated floor with shavings. No snow or rain can get in. All panels can be removed for summer, so they have a pen-within-a-pen to provide space until I open their coop into their 6 x 20 totally enclosed pen in the am; I work nights, so can't always open it early, and I want them behind two secure barriers at night. The attached cage is their "outdoor play area" for when the pen is too wet or drifted, and I keep the food and water in there to reduce moisture in the sleeping coop. We freeze most of the winter, so I'm using a heated dog bowl with a thermocube to turn heat to it off if temps rise. (The three gallon heated waterer for chickens was an even WORSE disaster than the awful user reviews stated!!!) Of COURSE the plexiglass & choroplast are installed over or under the cage WIRE.
I do provide some heat; I bought a sweeterheater and installed it on the wall, and it's plugged into a "Model TC035 Allied Precision temperature contolled outlet" to turn on around 35 F, and off around 37 F. It looks essentially like a large outlet adapter. Put it into the freezer when it arrives, then test it with a light to see if it works. Then I put it in the garage on a warming day, with a fluorescent light plugged into it and a thermometer next to it, so I could see through the windows what the temps were (from sun warming the garage air) when it turned on and off, as internet warns of many defective devices. It didn't seem to be working when I first got it, but the freezer seemed to have done something...who knows. It works fine. I prefer this outlet for the sweeterheater because the thermocube has a wide temperature range, and I'd prefer they stay fairly constant, but not freezing. I don't want them TOO warm, though, at night. Be aware there are DIFFERENT models of Thermocube (cheap) with different temp ranges, avail. online. The Allied Precision outlet is more expensive, but it has the tight just-above-freezing range that I desire.
We do, of course, use a remote thermometer to keep close tabs on things, and if I could have found one at the time, I would have gotten remote humidity sensor also. No humidity problems to date, knock-on-wood.
TIP: I use leftover HEAVY RUBBER (not plastic/polyethelyne) POND LINER for every project under the sun! I have strips stapled onto the sidewall of my coop, overlapping and resting on the lid of the nest box, to cover the hinge end crack at the outside wall nest box to keep out rain and snow. I also use it as a "drip edge" cover where my coop and cage join, to keep water and driving snow out. Always flexible (unlike plastic) too heavy to deform or blow around, lasts years, and cheap. I also use it to line raised beds to keep my water from flowing out between board joints in the summer. Works great.
Good luck!!!