Hi Ed,
I don't really understand but I can say that there's no signals in that circuit with a frequency of 2.4MHz. The sensor is supposed to work with a 32768Hz clock signal (which I'm guessing you're generating with the CCP module in the PIC) and SPI communication runs at a couple of 100kHz at most (depending on the clock frequency of the PIC).

Understanding is great but at this point you are just overthinking it. Supply power to you chips using as short wires as you can, place a capacitor across the supply pins of each chip - done. Voltage regulators usually wants/needs capacitors on both the input and the output, read the datasheet for the device in question.

/Henrik.