There should be wear indicators on the pads, take them out and have a look, if the pads are uneven, blued or less than 3mm of meat id replace them, make sure its the correct pads for the caliper! as a rule i always change my rears every 10k regardless and fronts around 6K if not before, YOU CANT SKIMP ON BRAKES! as for breaking a bolt this shouldnt happen, is the disc warpped? is the caliper on correctly?
Cant help with the other stuff never tried, Cheers