O3 - 2015 - 1.2 TSI - Replacing splash guards at rear brake disks, how much trouble to expect?

Hello,
the splash guards at my rear brake disks are badly corroded and will be, what I think would be called a "MOT-failure" in the UK next time it is checked. When replacing them, how much trouble should I reasonably expect? From memory when I replaced the disks some time ago, the splash guards seem to be hold in place by some pretty substantial hex-head bolts which I thought was surprising. My questions are:

Do the bolts tend to break when trying to undo them?

What is the safest method to get them out in one piece (e.g. impact gun or wrench)?

Do these bolts hold something more than the splash guards, meaning how much of a disaster is it if I mess up one and cant get the remains out?

Thank you very much in advance 🙂