Nick - In reply to your question on if the parking brake lever extensions are correctly installed or not, I'm going to say yes. The extension rod will only install one direction when connected to the rest of the parking brake hardware correctly.
Below is a screenshot from the above earlier mentioned Chevrolet Huck brake service film strip. The picture is showing the drivers side, evidenced by the blue arrow pointing to the parking brake cable going towards the front of the vehicle.
The red arrow shows the "flat" on the extension rod to be facing out, just like yours (your picture appears to show the passenger side). Also of note is the green arrow showing the anti-rattle spring on the extension rod where it goes over the parking brake lever. Your 2nd picture shows the spring in the correct spot, but missing from Otto's rear brake pictures.
I think you can confidently move on to the next steps of adjusting the brakes.
