Advice for newbie!

[Spacecadet]

I agree with all the above.

The toes are crooked, likely were crooked at hatch.

The scales of the feet are a bit rough, hard to know if it's the beginning of Scaly Leg Mites or just age/dryness, old hen's legs.
After cleaning up the bums and feet/legs, rub a little Vaseline or A+D ointment into the legs/feet, working your oil/vaseline up under the scales. Ointment will smother mites, if there are not, no harm no *fowl*.

Poopy bums can be from number of things. Deworming is a good idea. While you are cleaning up the girls, check them for lice/mites.

Broken egg shells don't look freshly broken. Could be from the hens picking at them, rat/vermin or something else depending on how predator proof the coop and run are.

I don't think there's any need to go in hot at or about anything. Just give them a good clean up. Clean out the coop, give it a good spray with some Permethrin poultry spray, add some fresh bedding and provide the hens with clean fresh water and fresh food. See how it goes.

Thank you very much for your thoughtful advice. I will be doing all of these things as soon as I can, I am moving into the house tomorrow and taking over caring for them.
I am still planning to have a conversation with the previous owners about the state they are giving them to me in, because they think this is sufficient care and that they are healthy birds.

They will be happier and healthier in no time! And I’m so glad to have found this forum, you all have been very helpful!