Rover, Circuit you requested is simple:
Its late so will try this quickly. (never is)
ONE opamp. Verify opamp output can drive to GND.
Input not going near ground so RR (rail to rail) type is not necessary except for output.
Hall output to R1 to neg input of opamp.
Opamp output to Rf to neg input of opamp.
Gain = 1 + Rf/R1 (actually negative gain, feed current in opposite direction).
Rf can be a POT to adjust the gain. Your gain is below 4, right?
Select the resistors large enough not to excessively load the sensor, yet not too large to be influenced by stray currents, in other words below 100k, 10k looks good for input resistor.
Opamp pos input connect two resistors, Vdd to input and Gnd to input.
Resistors are a Voltage divider (sets zero point), can be a 200K ohm 10 turn POT, zero adjustment. (single turn with two fixed resisters works)
Remember the ADC has its own reference, the Hall sensors output is ratiometric to ITS supply.
To accurately measure current, you must measure Hall's Vdd and adjust by any changes.
Better to drive ADC reference and Halls from the same single supply. Any changes thus cancel. DO NOT use an isolated supply to drive the Halls.
That's it. Going to bed, if you have questions...
Have fun,
Scott.