ECG, EKG, heart R-Wave monitoring: issues

The R-wave of a heart beat (specifically the R-wave) is from 0.5mV to 1.5mV. I would like to filter, amplify this and then read it with the analog pin of Arduino. I'm trying to understand and overcome a couple issues:

  1. the Analog pins give around 0.5mV accuracy by default.
    First, Will this be a problem?
    Second, is the solution to use v11 analogReference(EXTERNAL) and set the AREF pin to something much lower such as 10mV to improve the precision?

  2. most of the ECG schematics ive seen call for an OPAMP to amplify the signal with a negative and possitive voltage, such as in the schematic show in the spec for the AD620 OPAMP which calls for -3V and +3V (see page 12 of the linked spec)
    My current thought is to simply drive the opamp instead at +0V and +5V using the Arduino VCC for +5V and one digital pin set to LOW for a +0V drive. Is that the right direction or should I invert VCC instead for the - voltage? (and maybe some keywords on doing this).

willing and able to RTFM so keywords in response to this are fine.