And I'm also confused that this guy had these horses at his "hunting property" but is never there to care for them, they were out for days but he didn't know it, and still does not? And nobody knows how to reach this supposed owner. Well, he sounds like a really responsible pet owner.
I definitely think you are in ever your head with these three. If the owner (not that he should have them back either) can't be contacted, and the animal control can't offer you any suggestions, I think you need to find somewhere else for them to go. As uncertain as you seem about the basics, you don't need to get involved with three timid, maybe unhandled horses.
"Keep a leg on each side and your mind in the middle"