That bypass valve is only designed to work if the aftermarket cone filter is totally submerged in water. It was intended for lowered imports that have "cold air" intake that mount the filter down low... just behind the front bumper and below the headlights. So in theory a deep puddle could submerge those filters. You would have to be driving in water over your hood to need that, and even then the filter is at about the same height as the bypass... so I don't think it would be effective anyway.
Check this out, the filter is actually mounted BELOW the metal inner fender, probably only protected by the plastic splash guard. This is why those guys would use a bypass.
O2 sensor signal modifier thing... Junk.
Drilled AND slotted rotors, bad news. Drilled OR slotted rotors by a no name brand, not much better. If I were to run drilled or slotted rotors, I'd only get them from a well known and reputable aftermarket supplier. Wilwood, Brembo, & Baer come to mind. There is more to drilling and/or slotting a rotor then just putting holes or grooves in a stock blank. The metal composition, and cooling pillars are often different then stock to work well with a drilled or slotted design.
Brake covers... not my style but I don't think they'd do any harm either. I'd personally rather see the normal brakes, then a cover.