How is fall hunting different from spring? Is the focus on food?
More like flocking up for safety. In the spring, the hens don't flock up as much bc they are focused on nesting and if they bunched up to do this, they would be easy picking for predators. In the fall, they don't have to worry about predators killing their eggs/nests and therefor feel safer when flocked up. This is just my opinion but has been proven in the fall by busting up flocks and then calling them back. Trying this in the spring generally won't work..
What about using decoys and calling? Do they respond the same as in the spring?
Finding what they are feeding on in the fall is key to finding them. If there is nothing for them to eat they are not going to be there. Knowing where certain foods are will help in finding them, mast crops , wild grapes and different berries are a good place to start. Here in Pa where I hunt there are beech nut trees , it's the first place I check for scratching, I hunt with a dog which makes it a little easier, but I still have to hunt where they are. knowing what they want to eat eliminates a lot of ground