Duck introduces the right hand stuff by saying that it's meant to include the "under-utilized" ring finger. And sure enough, it does. My ring finger is beyond under-utilized -- I never use it. And my sense is that while it's essential for classical playing, it's optional for fingerpicking folk and blues stuff.

I have been trying (unsuccessfully so far) to use three fingers to create some african chora like patterns freeing the thumb to pick out a melody. I am told I should go see Charlie Hunter play his 8-string...

It's also needed for chord melody playing. I don't mean this in just a jazz sense. I'm using the term to describe pulling melody lines from chord grips for any style, like the African material Adrian mentions. The ring finger is a the first to pluck out any 1st string melody notes since that would be its natural hovering string. It may be followed by the middle and index if a triplet or some other notes are needed on the same string. This would also apply to the 2nd string if the chord does not use the 1st string. This probably evolves from a classical approach I guess?

I also use my ring finger lots when hybrid picking with a flat pick.

I think using the ring finger is more likely to show up in finger picking folk and blues playing where more "pianistic" chords, that is, more altered harmonies, are used. Some good chord examples might be 7flat5, 7#9, 7flat9, and 13 constructs. Often, they've already been stripped of uncessary elements, like the 5 or the root, just to get them into a 4 tone shape. You need to hear all of the remaining tones to establish the desired harmony.

I guess what I'm saying is that anything away from triads almost requires using the ring finger, unless you're just arpeggiating or strumming. Along with Duck Baker, Woody, Steve Mann, John Renbourn, and Paul Geremia come to mind as regular ring finger users in folk and blues tunes due to their harmonic explorations outside of triads.

1. Yes, I use mine, but don't find it essential. When I started, I used just thumb and index, then thumb and two. The use of nore fingers gives a fuller sound when required.

2. I sometimes rest my pinkie on the guitar to steady my hand, and dont find it affects the tone. I started off that way as I found it a help, but then got used to playing without resting on the guitar, so now i can do both.

I have recently begun using my pinky, which gives me a third picking finger. (So the pinky is for me, sort of like your ring finger, for those of you who play with your thumb). While I have a long way to go before I have fluent use of my pinky, I like having three fingers to play on the higher strings -- it helps with playing the first string when I play melodies.

I haven't included my pinky yet on my resonator, which I almost always use fingerpicks on. Maybe after the pinky catches up?