-B,+W = 5V and W appears to be the signal line.
-B,+R = 5V, supply
part 2: both a meter and the scope report the same frequency which is dependent on the speed, however, shouldn't RPM = 1/freq * 60? The RPM display and a tachometer both report 145-147 RPM but the frequency is 39Hz, which is again leaving me scratching my head. It's unlikely there are 3.71 slots. So what gives? This difference more or less is observed through the entire range.