I would start from scratch with the brake lines. the nickle lines aren't all that much money and you can then know for sure there aren't any other little surprises from the PO.
that doesn't sound encouraging. It's pretty easy to grab the comp numbers though. I'd probably still do that so I could see if it's across the board or just one failed ring.
MJs have a special bleeding procedure. if you don't follow it exactly, you can get air trapped in the emergency line. you can find it in the link in my signature.
this is probably not wise advice for a daily driver, but for an occasional dump run truck, keep it topped off with gear oil and you might be surprised how long it'll keep going.
your money isn't going towards a 3rd vehicle, it's going towards keeping your 2 best vehicles from ever getting near the college. think sacrificial. like a winter beater.