[BillA]

eh ?
for the liquid side, sure; air side about zip, never will 'know' the mass/volume flow
no, rad exit to air (as is presumably done); pressure in area of unconstrained exit flow is I think sufficient for a differential pressure reading

this dP can be had with some precision; how sensitive such is to the tip configuration and placement needs to be assessed, I agree
(same readings from several similar positions = 'ok' tip effect ?)

when I get some data I'll send it round