[hypoxia]

Steve, your labeling is accurate.  There is a check valve in the Headhunter pump at the inlet from the tank.  There is an adjustable pressure switch (your Pressure-Stat) in the Mach 5 pump (see photo), turn clockwise with an Allen wrench to increase pressure.  It will change both the low and high pressure points at the same time.  What you call a Pressure Pot, Headhunter calls an External Pressure Tank or Accumulator.  It is normally set to around 32PSI but I set mine to 38PSI after I increased the Mach 5 pressure to turn on at 40PSI for better flushing.  The 1" white PEX is for the Headhunter Toilets.  If the build called for other brand toilets that line may not be there.  The Blue PEX "To Fixtures" goes to what I call the BrassCraft Valve Panel which is Newell's version of a Manabloc.  It allows plumbing fixtures to be isolated without affecting the other fixtures.

The pump will not come on with city water psi above the Mach 5 cut in pressure ~32-40PSI assuming your water pressure regulator is set for a higher pressure.  My regulator is set for around 65PSI.  

My Autofill Switch Solution