About
Challenging traditional. This arrangement is (I believe) very much the work of Stefan Grossman, an American country blues guitarist / teacher / writer. Check his instructional material. Really helpful, because he does not only explain the "How?" but also the "Why?".
Original Key
No idea.
Tuning
Dropped DG (DGdghe)
Tab Notes
Not easy to play walking bass and the lively melody simultaneously without getting confused. Requires an independant right thumb with some own "free will".