First - check the alignment of all of the accessories on the engine - they should be very close to exactly in line. This will cause the type of fraying you saw on the belt. Possibly something wasn't re-installed right during the headgasket job.

Second - belts don't like oil - that may have been the cause of the failure.

Third - if I'm right, the air pump will only run briefly (like 100sec) after a cold startup - injects more air into the exhaust to help "light off" the catalytic converter.

Fourth - don't know about access to the wires, sorry.