Margaret, I learned the tune from Delores Keane as well, and use the same chord progression, but have never tended to play the passing G chords as you listed them nor tuned my bottom string down. Trying it your way, I noticed, adds interest to the tune (although I didn't tune down for my run through). One question: with the low E string tuned down, do you then use a D bass for the G chord or play the fifth fret G?