Howdy!
For best result, watch your pullets and watch the land. Chickens are amazingly destructive. It's a bird thing, really. It's all based on how they are designed to find food and what effect that has on the surroundings.
Chickens are very, very good when combined with other animals. What they do helps by breaking up other animals' manure, removing pests and parasites, eating seeds, eating insects, scratching up and mixing things into the soil, and otherwise being the fluffy tiny rototillers they are.
If you are in an area where the ecosystem is more fragile and tending wet - wetlands, rain forest biome, and similar - I would suggest getting ducks and or geese. Geese graze. They are ruminants and their primary food is grass and plants; they don't need
water but greatly enjoy it. Geese must have enough water to cover their bills so they can swallow and rinse their bills. Ducks eat water plants and insects, apparently preferring things that tend to be around water. They need more water than geese for health reasons, but don't *need* a
pond if you are able to change and refresh their water containers regularly.
Neither geese nor ducks scratch or are as blindly destructive of their environment as chickens, though geese will eat quite a lot and ducks are very capable of being very destructive - they do it in a different way.
Because of the time it takes for the land to recover from chickens being housed for several days, for the lightest possible touch and to quickly help the land regenerate, you might try a few simple things - keep them in a smaller than recommended area depending on what your land can tolerate, move them frequently - every day or two, water the area they were just on well - this helps to get the plants a start on recovery. It washes all those nutrients into the soil, gives the plants a chance to reset and start growing again, and puts the finishing touch on the whole purpose of moving your animals around.
You will find that different types of chicken will do things differently. Those three lovely pullets will be more likely to forage a bit, but not be little rototillers. Buff Orpington are more active than some breeds, but still very calm birds.
Chickens prefer to eat seeds and insects. They will eat meat and ... everything you give them. They are omnivorous, but fruit is higher on their list than seed and both are beaten by meat of any sort. You could
feed your birds raw fish, cooked poultry, cooked eggs, or anything you might eat (with certain exceptions), but they aren't going to eat grass like a goose or duck would. They will eat it, please don't misunderstand me. It's just not their first choice.
Yes, make sure they have a dust bath in a protected area or they will make one to suit themselves.
Enjoy your girls and try not to stress.
How much space do chickens need? Article.