1. The valve cover gasket has nothing to do with the oil on your spark plugs. If the spark plug seal is worn out, which I doubt, the oil on your spark plug will be on the outside not on the threaded side where the spark occurs. You might have a larger problem. You should've checked all these prior to deciding to turbo your car man.

2. This is the first time I've heard of stealthmode's feed line not fitting onto your turbo. Can you clarify which fitting on the feed? If you are referring to the female ends of the steel braided line, then you are wrong..... those are "FLARE" fittings. Do NOT use any type of sealant/teflon on the threads. The sealing surface of those type of fittings is not the threaded area. It's the actual flare (the nipple looking section).

3. You have no choice. You'd have to get that DP customized. Also, O2 sensor wire is not that hard to extend.