High levels of oil on cylinder heads

Do you mean the spark plug wells are filling with oil?

The good news is the oil in the spark plug well is from a bad valve cover gasket. This is an easy fix, just replace the valve cover.

I'd assume the oil on the alternator is from the crank shaft seal. The crank shaft seal usually lasts forever unless the PCV system fails or the motor oil isn't changed.

The knock could be from the engine running to lean. I would say a bad front O2 sensor might be the cause.