I have kept a good number of chickens free range over the years. Recently I have allowed one of my flocks to roost on front porch in part enabling more observation. Flock has been made up of American dominiques, American games, red jungle fowl, and crosses made up of latter two. They have feeding stations placed around property and multiple vegetated fence rows providing cover from elements and predators.
First response to reduced temperatures is increased feed intake. I provide different types of feed at the different feeding stations. The quality layer pellets are provided at a fixed amount per bird while the scratch grains and black oil sunflower seeds (BOSS) are provided free choice (all they want). The intake of layer pellets has been fairly constant but intake of scratch grains and BOSS shoots up when temperatures drop. Feed intake can nearly triple when temperature drops to -10 F and wind is stiff. BOSS seems to be targeted preferentially over scratch. Birds also seem to go to roost with more filled crops when temperatures low during day prior.
My birds also tend to avoid wind and when possible stay in sun when temperatures drop. They seem to have well developed recollection of where good cover site from elements are as day progresses with changes in where sunglight is coming from and wind direction. During extreme cold birds feed tend to feed in burst then loiter in the covered areas if such areas are close together. If food and cover areas far apart they tend to stay with food.
In my area snow can be significant. They tend to avoid walking in snow when possible. My feeding stations are elevated on straw bales so they are not covered when snow is deep. The games, red jungle fowl, and their hybrids readily fly between feeding stations. Distances last year pushed 200 feet between stations and birds could hit all without walking through snow except immediately around feeding stations.
Social problems are greatly subdued. Roosters will barely fight and birds will literally touch each other when seeking protection from cold. Feathers can be greatly fluffed up to conserve heat.