My painful discovery charted
here may be of some help.
What I got from it was:
Flow: digital.
Pressure: analog or digital.
But if I set the flow rate at 0.5, 1.0, 1.5, etc, then I have, allegedly, a 5% error source (installation notwithstanding).
Analog: possible?
As for the pressure drop, depending on the unit, it may require a more powerful pump, but that's not really relevant, until you consider the added heat. (IMO)
Note the suggestion from Bill for a magnetic flowmeter. That's a top notch way to do it!