Ive never have seen anything like this before. The best thing to do is to keep cleaning it. DO NOT try to perform any type of surgery or medication without a vet.
The only thing i could possibly think of is a opossum, but i still dont see how that can leave no trace of an attack or open a nest box. If a preadetor did do it would probably kill all your chickens. Since silkeis are small birds maybye it got out through a small opining or you missed closing...
Chickens are pretty hardy when it comes down to weather. At that age it should be fine for them. But if they dont want to be outside, trust me they will let you know.
Im sorry, i cant really tell wether those chicks are either. But if your chicks are one week old and you want to determine the sex of your chick, you need to find the tail feathers. The tail feathers is a sign that it is a hen an the first two weeks of age, if there is no tail feathers at that...
The Buff Orpington is the favorite in my flock. But here in New England when temperatures get cold. They are big and heavy birds that are capable of surviving below 0 temperatures. Im not sure about doing so well in heat because of their big body. But be sure to provide your chickens cold water...
The garbage can is a good idea for rodents and ect. But i do reccomend you get a feeder that is bigger than yours , when your chicks grow older. I say that because it will be uncomfortable for your chickens, and the food will be much more dirty due to rodents, poop, bedding.
I personaly think that pinewood shavings is the best for your chickens, and here is why. Pinewood shavings are very good at killing off bacteria from your chicken's waste, and they also help to absorb the exess moisture that is built up in the coop. Many other types of bedding will have bacteria...