Marc and Arthur:
I can comment just on the resistor issue for now:
We're talking about the same thing when it comes to resistors and radio interference. The reason for the resistors is to reduce (or suppress) radio interference from the secondary ignition system. It is my opinion, and I believe this will be confirmed by consulting a Bosch spark plug catalog, that the "R" in a Bosch plug indicates a resistor type plug. Again, the only purpose I am aware of for the resistance in the plug, or in Mercedes case resistance in the secondary ignition wire end, is to suppress radio interference. There is no advantage, and in my mind a disadvantage, to having resistor spark plugs combined with resistance designed into the secondary ignition wiring.