Dreamer:
Good question about spakplug antiseize.
The first thing I do when buying a vehicle, new or old, is apply a bit of antiseize on the sparkplug base threads. Lawnmowers too, come to think of it.
However, these antisieze coumpounds have metallic copper, lead, maybe zinc, which will poison your catalytic converter……so apply very little. I own a fair number of engines, and two tubes of antisieze are still about half full.