EWS is a security feature that must be disabled with most custom proms. If you pop the hood, there are two circular harness taps next to the fuse box. There is a solid green wire that must be clipped. I'm positive it's green, and I think it's #6. That will solve your problem.
Floating rotors were offered on the earlier E36 M3's, and are one of BMW's best designs. They provide for excellent heat disapation, and can be pushed to great limits. Your big brake kit is better, but it's just not worth the expenditure. If it's not your $$$, well then bonus for you. BTW, four piston calipers aren't really better than two piston calipers, at least the engineers at ///M that designed the new ///M5 don't think so.
I'll ask Steven again why he said skip that thermostat. I forgot why. I was gonna do the same, but didn't after he said not to. When he says do or don't do something, I listen, the why isn't as important.
The metal impeller pump is a good buy. BMW actually went back and forth with the plastic and metal impeller, the jury is still out. Both fail, but my money is on the metal impeller as well.