This isn't confined to the rear brakes - sadly the fronts can suffer in the same way too. Rapidly corroding cast iron reaction frames have been a feature of every cheapish car I've owned for the past 20 years, and I've needed to do regular maintenance as described in my linked post. If you clean & lubricate after every winter they'll be just fine, & will still work far better than stock if done every 2nd year.
Very likely, unless the reaction frames are cleaned & lubricated as I've described in my linked post.
At the design level, stainless steel inserts in the reaction frames would almost certainly eliminate the pad binding problem. That would be a useful mod but would add a little to the component cost of the car. Very unlikely to happen IMO.
From a functional point of view, I seriously doubt the 1.4 has sufficient performance to benefit from rear discs & the car would likely be better off with drums at the back. I suspect the decision to fit discs has been taken by marketing, not engineering.
