The 102 is a very nice derailer of good quality... the fixing bolt should not be a problem and in many cases people don't tighten them sufficiently. The cable that passes through should be compressed to half it's diameter if it is to stay put.
If that fails a lock washer could be used but I have never had to resort to this.
If the cable is badly frayed it needs to be replaced and when you set it up the cable should have no slack and the response from the shifter should be immediate.
Cap off the cable with an end or solder it to keep it from fraying... I like solder for the neat and tidy appearance it gives and because it allows you to remove and reinstall the cable easily.