Are the threads on the inside (junction box?) the same as the threads that go into the caliper. Also, how long is the line that goes from the PS rear caliper to the rear junction box?
I'm gonna have to replace at least the caliper line fitting, but I might have to replace the line as well.

Unless you crushed it, you will not have to replace the line. The cupra-nickel lines do not rot.

There are a number of threads here that tell you how to fix the twisted line at the fitting. I short, you buy a short piece of line with the Euro double-bubble-uber-flare on it (even better, find and undamaged 5" section with flare and nut at the PnP). Cut the line on your car above the mangled section. put a standard flare nut on it and flare it with the $12 kit from Harbor freight. Cut the line you bought, put a standard flare nut on it, then flare with same tool. Attach the two lines together with a standard flare coupler.

Now you likely have a piece of coated steel line in your braking system but it should last at least 5-10 years.