Don't know about too many others, but Rufus Crisp generally changed tunings so that he could incorporate as many open strings and second-fret (actually, he filed the frets off his banjo because it wouldn't play the notes right) pull-offs and hammers-on as possible.

re "frailing"--it's a southernism for beating or striking---"behave, or I'll frail you good!--quite synonymous with flailing, beating or rapping. As I recall, the term "clawhammer" was originally used for three-finger picking, where the thumb and two fingers resembled a claw-hammer. I don't know how it's come to mean melodic drop-thumb frailing.