It's really generous of you to offer to help this boy
.. I am in CT as well, there is a couple things I would suggest as well as the advice given.
First if you take him, I would start off with a good vet workup. I'd keep things low key for a few weeks and let him re adjust to living IN a house. His potty problems IN the house where he is, could just be from not letting him OUT to potty vs a behavioral issue..If he's fine with a crate, then yes, definitely crate him when you aren't home, can't supervise.
I'd treat him like a new puppy with the housebreaking issue, since again, it may just be an issue of taking him out.
If you want to look into obed training, that's great but i would give him time to settle in and get some of his medical issues under control.
If you want to feed RAW, there are two great sources here in CT,,Bravo or Oma's Pride. You can google either, there are distributors around the state or you can go directly to the source.
Not sure what part of CT your in, but if you want to pm me with your location, or put your town/city location out there, some may be able to reference a good vet in your area..
Good luck with him, it sounds like his issues may be from lack of care / continuing care by owners/ leaving him in the basement is NOT a good thing for him.
Please keep us updated on him