Re: oil on plugs
I would suggest a leaky cam cover gasket. Both numbers 1 and 4 are prone to this, if he looks down the plug holes he should notice a residue of oil round the apertures of the plug holes. Obviously solution is to replace the gaskets (the larger outer one and the smaller inner ones) but I also bolster my gaskets with a little gasket sealant and this seems to prevent leakage. Do not overtighten the cam cover when putting back on, this will cause gasket problems also!
One word of caution. On number 1 the larger plug (to the left) is the one prone to leaking, but if you also have problems with number 4 it is often the smaller of the two plugs at the very end. Leakage of oil round the plug doesn't do this plug any good at all. Being smaller, it is less robust than its bigger brother and the outer casing can deteriorate. I have seen this smaller plug shear off, leaving its thread inside the head! So if this is leaking be careful to remove and replace the gasket asap. And also make sure when replacing plugs do not overtighten!!