The e-brake cable has leverage that you probably can't produce with your hands and a pair of pliers. The caliper is probably working. If its siezed then the rotor will look like a rusty piece of shit.
The e-brake cable.probably needs adjusted. The brake lines could use some new fluid in them im sure.
You can free stuck calipers pretty easily. To free a stuck caliper get the side in question broken down with the caliper removed( only the caliper being off is nessicary). Have a helper slowly press the brake pedal with the car off, while you watch the piston. Don't get too crazy with it, you don't want the piston to pop out. Also, with rear calipers they take a turnback tool or some stupid shit. So even with a nice new caliper its still a PITA to push the caliper back in.
Basicly rinse repeat until the caliper is easy to push in and out. If its really siezed you will need the vaccum boosters assistance.
If the e-brake cable is siezed up, adjusting it super tight, then jerking the e-brake should give it some play. Once it has play you can spray some PB Blaster on the cable where it travels inside the sleeve. This should help completely free it. Then you can get some grease, like disk brake wheel grease.
I gobbed A bunch on my 87 Crx's brake cable and it helped greatly, I just had to pull and release the cable a shitload of times., which started sucking up the grease.
Be careful when trying to.break loose the bleed screws, you don't wanna get one that's a little stuck and break the bleeder offf in the caliper. Spray PB blaster on the bleeders and come back to em in 30 mind and recheck them, if not freed up spray some more and give it some more time.
A set of small wire brushes to clean things up may help. I once sprayed some WD-40 between the rubber boot and the piston before pushing the piston in and out around 20 times.