trking8, I only play acoustic these days. It would be ridiculous for me to try and separate my arm from the lower bout of the guitar, thereby "floating it."
So I just checked what is going on and my arm rests on the edge of the bout below the elbow joint. But it isn't anchored there per se
, but instead is slightly mobile in that it rubs around just a little. Then, on the hand itself, my fingers that don't hold the pick are slightly open, just about exactly the way Weir's hand appears in videos. The fingers are constantly just grazing the surface of the top. Because I don't manicure the nails as much as I should, the wear and tear on my guitar comes from fingernail scratches rather than pick miss-hits of the strings.
For you, if you want to follow things further, you might want to experiment around with things like keeping your wrist parallel to the ground, much like the old fashion locomotive steam-engine connecting rods that tied all of the wheels together,
“I wish I was a headlight, on a northbound train…”
just to see what that feels like, or moving your elbow sideways, like when Weir makes it seem like he's doing little circles of the whole hand to play closer to the fingerboard on in-between strokes, etc., etc. There's no end to this stuff.
Really, I don't think about it anymore. My biggest problem is oils on my fingers transferring to the pick, I slightly miss-hit the strings or just go into a trance, and my pick goes sailing away.
One cool thing about the floating arm (or hand) is that you never know exactly what you're going to hit on the strings, great with an acoustic but I don't know with an electric, been so long ago. I generally always have some sort of chord base, like an "open G" shaped chord or something, placed on the strings that allows the miss-hits to be incorporated into whatever results. Keeps things exciting and slightly varied.