All fixed!!!
Parts (driver's side rear)
Duralast Reman Brake Caliper - C628 - $40 (after $30 core)
Brakeware Brake Hose - 70757 - $16
Tools
3/8 ratchet
12mm (caliper bolts; at least my new ones were)
13mm (banjo bolt; holds flex line to caliper)
15mm (caliper bracket bolts)
9/16 wrench (hard brake line fitting going to the flex line)
10mm wrench (bleed screw)
17mm wrench (caliper slider bolts; you'll see what I mean)
small flat screwdriver
medium flat screwdriver
(I think that's it)
The caliper came with new slider bolts (no grease included), rubber boots for the slider bolts, caliper bolts, along with 3 aluminum shields (so they seemed; you'll see them when you take it all apart).
The flex line came with new copper washers, but did not come with the banjo bolt (so you'll need to re-use your old one, or buy a new one). It also did not come with a new clip to hold the flex line in place where the hard line screws into it. I re-used the old one as it didn't break upon removal.
The removal of everything went pretty good. I soaked everything with PB Blaster before starting. I also heated the hard line bolt/fitting/nut. Instead of applying a large, constant force on it, I tried just putting the wrench on it and hitting it with my palm. Seemed to work good for me anyways.
The caliper was obviously bad. The cup was covered in fluid and you wouldn't believe how much sand/dirt/small pebbles were stuck to it. I replaced the flex line just because it was easy to replace while I was at it.
Didn't really have all that much fluid to bleed as new fluid had already filled the line. Only had to cycle the pedal 6 or 7 times until no air came out.
Now I have a solid brake pedal again!!

I'd still like to bleed the other calipers though.
Anyways, hope this helps someone else somehow!