The oil on the K&N and foam filters is to trap the dirt, i.e. filter
Dynos of "performance filters" have been beaten to death over the years. The only improvement is sound at the expense of increased dirt in the engine.
increased air flow = bigger holes = more dirt can get through.
The other way to increase air flow is to increase surface area. The paper has more surface area than the K&N.
Yes, oil will kill the MAF. And based on what I've been reading it appears the M2 MAF is closer to the box than in the past. Haven't confirm as it would require me to get off my butt and open the hood.
Lastly, you guy probably know more than me, but my understandng of turbo vs. NA is that the improvements are between the turbo and engine, e.g. intercooler, which of course assumes the turbo is getting the proper amount of air