Presuming your brakes are similar to mine...

Yeah, those rear pad backing shims did not fit for me with the PBR pads either. Just as well, they were deteriorated.

The rear rotors will hang on the parking brake if the lever that actuates them is frozen (like one of mine was). Not anything to be done about it that I can think of, since the adjustors are not accessible from the back, as they are on many other cars.
They dig themselves a groove over time, and catch on the ridge. Ah, the joys of drum brakes...

I would hope that you would not need to test new rotors for runout. Never observed such a problem.

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1986 300E 5-Speed 240k mi.