The pics help a lot. This does't look too messed up with brake fluid or rust. This parking brake is easier to deal with than some - good news. It doesn't show any wires in the pics so ABS may not be on the back brakes at all ?? Dunno on that.
What might be happening is the backing plate has worn a slot such that shoes don't retract. That happens when lube which is put on a pad of backing plate has expired and the metal of the shoe makes a worn in spot - more common when brakes are under adjusted and travel farther to contact the drum and can make a popping noise going oved the groove made unseen with shoe in place. If you look at outer edge of the metal of the shoes there will be a "v" type dip in the metal on the outside showing where it would contact the rubbing spot on the inside. Note - the shoes are such that the metal can be used on either side.
There's a "star" adjuster at the bottom that freqently doesn't turn to self adjust these and the sharpness of the lever to star gets worn - about all do this and need periodic manual adjustment. With shoes off you could scrape down the backing plate and relube it, take star adjuster apart and lube it all up, clean drum and shoes with "brakleen" (don't get that on rubber parts) lightly sandpaper the shoe's lining and when reinstalled and adjusted up they would feel like new. Hard to see but they don't look so evenly worn and cutting the drum might help as shoes don't look worn out - hard to see that close.
That pic show the metal rod that goes from top anchor to the pivot arm for the adjustment. Not seen clearly is a bar under the wheel cylinder that connects front and rear shoes and should have a spring on one end. If you look where the park cable comes in and attached by a ball or barrel at the end of cable with spring around just the exposed cable that when pulled with the cable moves the lever and the bar pushes both shoes out to contact shoes to drums. The connecting bar spring should have some small room to compress if you just push the connecting bar by hand. If not - try prying back the way the spring on cable is pushing where it connects towards "retract" and if that moves and then allows the connecting bar to have the semi-loose spring when you do that then the cable isn't fully letting go. I don't think there a problem with that right now but rather the backing plate to shoes have worn in a grove that inhibits the free return of the shoes to "home" position.
I don't see enough brake fluid in there for alarm with just these pics.
If all that check out then removing the parts, scraping the contact area of backing plate, lubing it and lube up threads on star adjuster and the tip that will come off with "specific" brake lube grease, adjust it with the star and a "spoon" is the name of the tool but a screwdriver can work such that shoes in home position - as seen by contact all the way back to the round anchor at top and bump shoes to set in place (hard to explain) and adjust the star such that shoes move out. Out is closer clearance between linings and drum in the direction the lever would turn the start. Many are reverse threaded for one side of car. Adjust so you can put the drum back on and it will fight getting over a rust ridge with drum not new or just turned but should go back on and spin without rubbing but close. There's a puch out slot so you can adjust these in backing plate or perhaps thru drum but you don't need that if they aren't punched out now with a oblong rubber plug that fits in those. If adjusted too far you need to hold that lever away from the star to go the opposite direction. When you have to do this thru the punched hole you need the real brake spoon and a little screwdriver to hold that lever away from the star as it won't turn to loosen adjustment with it touching. Confused enough?
That stuff is second nature to me and confusing the first time you see it all happen which I wish you could just once dammit.
All those springs and things look confusing at first till you get the idea. In putting this all in there are times when the parts all fall to the floor and you just go back one step at a time. Use an untouched other side as a reference or take a pic before you start. Remember the right and left sides are mostly "asymetrically" opposite such that things are postioned regarding the direction of rotation which is yes the same as it rolls but placement is "towards front" differently - just a mirror image if you will.
Again: Shoe with more lining goes to the rear end of the car. That shoe does more work than the front one and when you hit brakes while going in reverse the rear shoe will pull away from the anchor up top against the return spring which pulls on the metal rod and if enough motion before shoe contacts drum will turn the start a notch which makes it self adjusting if everything is free to work. All lubed up some mindless hard stops in reverse can do a final adjustment of the back brakes.
Those being properly adjusted will make the parking brake work better and sooner (fewer clicks) to hold the car.
Again II: no parking brake cable adjustment is called for unless one is replace or a new brake job doesn't work or parts fit right almost always because it was adjusted improperly once before but this car has so few miles there's not so much chance you are battling mistakes made before you got it.
So for now what I see is the need for clean, lube and adjust and the possibility of getting the drums turned might help a lot. I'm not sure the wheel cylinders are the issue from the pics. If they are free to move (you could see this with drum off and someone pushig brake but just a tad till the first motion then quit or piston of wheel cylinders could overextend and fall out - don't let that happen please, or with shoes removed you can just push the slotted bullets that go into ends of the wheel cylinder back and forth to proove they are free. You're there, I'm not so your call on replacement of the wheel cylinders.
This isn't wasted learning with this stuff as drum brakes are still out there and some vehicles are using a small drum inside rotors for the parking brake. Each a little different but similar ideas prevail.
Ok: Now ask back at what I just confused you the most with!
T
Tom Greenleaf - MetroWest Boston - USA
http://www.acsource.com/ _________________________________________
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Using pipe cutter to remove metric flare nut Follow the directions to use the double-flare tool. You will need to smooth out the outer edge of the pipe with a file and use a deburring tool (or a large drill bit) to smooth out the inside edge of the pipe. 
Double-flare tool with pipe clamped, ready to flare (note both flare nuts are in place on pipe) REMEMBER TO PUT THE FLARE NUT ON THE PIPE BEFORE YOU FLARE IT OR YOU WILL HAVE TO CUT OFF YOUR NICE NEW FLARE AND START OVER! Put the flare tool's pipe clamp on using its 3/16 inch hole, expose the required amount of pipe, clamp it down, attach the 3/16 inch adapter, screw it down on the pipe while watching the pipe to make sure it doesn't slide out of the clamp, back out the clamp and remove the adapter, then finish the double-flare by screwing down the flare tool into the pipe. It's easier than it sounds, just follow the directions that come with the tool. Repeat for the other brake line end. If you screw up the brake line you can buy pre-fabricated 3/16 inch brake lines of various lengths at an auto parts store, you just have to bend them to fit. They are pre-flared and have the metric or standard flare nuts already installed. 
Making the first part of the double-flare with the adapter Blow some WD-40 or other solvent through your short line and then blow compressed air through the line to dry it out. Push the brake pedal a little to flush some brake fluid through the line coming from the master cylinder-this must be done to remove any debris that got into the line during cutting, sanding and flaring. 
Making the second part of the double-flare without the adapter Warning You must torque the brake line nuts to 113-190 inch pounds! (about 10-15 foot pounds) If you don't you run the risk of having a nut come lose and dump all of your brake pressure which will result in total brake loss! (The parking brake may still work) 
The finished brake pipe with flares at both ends Rob Robinette