As far as cleaning the brooder the main thing is to keep it dry. A wet brooder is unhealthy and will stink. The brooder can get wet two different ways. One is obvious, if water gets spilled or the waterer leaks. The other is from their poop. They poop wherever they are, day and might. If it builds up too thick it won’t dry out.
You say you are using pine chips as bedding. I wonder if that might be shavings instead of chips. Doesn’t matter, both can work. The purpose of the bedding is to act like a diaper. As long as the bedding stays dry enough it will absorb moisture and things are fine. If it gets wet though it can’t absorb any more and it can start to stink. Good ventilation and keeping it stirred if it starts to build up can help a lot but it may eventually require changing.
I never saw where you gave your location so I have no idea what you mean by cold. With their down coat chickens don’t feel cold like we do once they feather out. You’re a hunter, I assume you have some pretty warm clothing. Try wearing that around inside the house for a while, you’ll see what I mean. Most chicks feather out at 4 to 5 weeks. I’ve had chicks go through nights in the mid 20’s F at about 5-1/2 weeks of age. Once they feather out you don’t need to give the chickens a warm place to stay, you need to allow them to keep themselves warm much like the wild birds that overwinter where you are.
What they need is a way to get out of the wind. You may have experienced wind chill, but there is more to it than that. The chickens, like the wild birds, trap tiny pockets of air in their down and feathers. That insulates them and allows them to keep themselves warm. If the wind ruffles those feathers so those air pockets escape the bird can get cold. The way the feathers lay if they can face into the wind they can handle a stronger breeze than one hitting them from the side or worse, the rear. Still, they have limits. So in the coop give them a way to get out of the wind. That includes on the roosts.
The other issue is moisture. If moisture builds up that can lead to frostbite. The moisture can come from their breathing, their poop, an unfrozen waterer, or maybe snow or rain blowing in. You will never get the inside of the coop drier than the outside air, but if you can approach that you are good to go. You can’t get better than that. The way you manage that is good ventilation, exchange bad air inside for good air outside.
There are different techniques to manage good ventilation without having a breeze hit them. To me the easiest way is to have the ventilation high enough so any breezes blow over their heads when they are on the roosts. You don’t need to keep them warm, you don’t need to provide any heat out there for them, once they are feathered out. In warm weather they like a cool breeze blowing on them, but in winter if it is really cold wherever you are, you don’t want to build a coop that becomes a wind tunnel where they cannot get out of the wind. You also do not want an airtight box that keeps their air stale and moist.
When can you move them to the coop with no supplemental heat? Some of that will depend on what the temperatures really are. If you are going to stick around on the forum, and I hope you do, modifying your profile to show general location can help with a lot of questions. Acclimatizing them can help a lot too. If they are exposed to cooler temperatures just a little bit they can handle the move to the cold easier than going straight from a tropical climate to the arctic. Some people take their chicks out and allow them to spend some time in the coop or maybe forage on the lawn during the day to get them used to somewhat colder temperatures. I raise my chicks in a large brooder in the coop. I keep one end toasty in the winter but the other can cool off, sometimes below freezing, so my chicks are acclimatized. That’s part of why mine can handle those temperatures so well.
You will get some pretty wide opinions on here about when they can go outside without supplemental heat. Some people go a little earlier than me, a lot wait a lot longer. To me it is a function of how cold your coldest extreme will be, how well your coop protects them, and how well they are acclimatized. But in general they can go a lot earlier than many people think. Since you already have the chicks I think you need to be building that coop. They grow really fast and with potential smell, noise, and the dust they make when brooded in the house it may not be long before you want them out.
Since you were hunting I’m assuming you are north of the equator, not south. If you are south with the weather warming up you may not have much to worry about with the temperatures and them moving out. In any case hopefully you had a good hunt. I enjoy that time out, even if I don’t get something.
