Very interesting all here !! Heres method # 4568797787404048<><>>>< One very simple thing from your first question leads me to ask if you have found a map for yourself on figuring out where your hitting. The thumb can be a route as a measure when it comes in contact with the fith string. In a stopped possinion feel and mentally measure the distence of your down-clucking fingers from where the thumb rests.First string is the farthest second closer and so on . I use my middle finger out at first and second strings and index up close at third and forth .(Unless something is bleeding ! ) I also use my pinky for subtext but all of it is measured from the distence of where the thumb lands. Its the same for figuring double thumb. Thumb on 5th string (cluck cluck) and then say thumb on 3rd string the measure to first of second comes from the intervel of space set as a measure from where the thumb hits.
                Oh yes you also said something about picking with the thumb. Something about that thinking, I amagine might   get you in trouble. In the rythum of comming down on the first and second clucks the thunb is resting on the fith string for measure (like a claw coming down and on the third move you are realy just bringing the thumb away (Down or out I dont care). The simplisity of this is what can give it the speed for a hoedown!. You'll find if you try doing somthing extra with your thumb like picking that you'll get a charley horse you wont forget
                  Im sorry as others have said above if you do this for 30 years its hard to pass it along in print. Have a great time at any rate. All the best , Guy