I can partially answer you question/s.
My car calls for Bosch Triple Electrode plugs ( 2000 C 230 Kompressor ), so that's what I use.
My experience with + 4 plugs in some of my other vehicles have been mixed.
Some liked them, some didn't.
The fact that I own a 5-gas exhaust analyzer, where I can see minute changes in Hydrocarbons, helps me evaluate the benefits or downfalls of these " miracle " devices.

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2007 C 230 Sport.