So I have about 2 years under my belt with small hookbills, but finches are a bit of a mystery to me. A couple days ago, someone left these two gouldians at the pet store where I work. He'd only had them about two months, and said they were both male.

I'm not sure if they ARE both male, or if the black face is a hen, or dilute, or if the feathering is dull due to age or nutrition. If both are male, are they likely to continue living together in peace as they mature?
I've been doing some reading because I'd like to adopt them, but now I've become a bit paranoid about the threat of air sac mites and I'm hyper-focusing this one issue. I really don't want to risk the health of the bird that I already have, and I need some help finding information that is easy to understand regarding them, risks, treatments, etc.
I also have some concern over their feet and beaks. The beaks look to me like they just need a good conditioning perch to rub on, but it's hard to get a good image, they're very flitty little birds. As far as I know, these birds have only had a single dowel rod perch. You can see how peely the feet are, but I'm wondering if this might be a humidity issue as I doubt they've been misted or had many bathing opportunities.
If anyone can help me with some of these concerns, I'd really appreciate it. I'd love to give them a good home, and I do have the ability to QT them in a separate air space, and have a relationship with a vet familiar with treating birds.
Thanks!