Hi, I'd get some white grow light for fill spectrum winter lights.
Do they have any type of covered run?
I'dreccomend to get an flock feed, I like nutrena. You don't want to give them to much extra fatty treats, chicken store fat around their organs and too much fat causes health issues and death.
Not safe for cats but as long as the cats aren't licking the birds, it's not really an issue. Poor the dust in an old sock and "Bop" them all over with it.
The first attack is always the hardest, I'm sorry.
Since they weren't secured on your property, you may or may not be able to ask for anything except payment of the birds, about $30 each. Remember to stay calm, kind and reasonable.
It needed to be removed, but it usually don't require cutting, per se but it's like a zit.
https://www.backyardchickens.com/articles/treating-bumblefoot-a-simple-surgical-approach.75146/
That's a lot of white for a female barring. Properly bred barred Plymouth rocks, are odd to be sold straight run because it should be obvious at hatch what the gender is.