I read a good biog of him a few years back (can't remember the author but ABE Books or somewhere could probably turn it up if it's not still in print) which explores some of the darker areas of his life without getting lurid or cheap about it. Apparently the love of being whipped stems from his mother punishing him in childhood in this manner, and his response to it somehow became conflated with desire. Writing from memory, but it had to do with Mama, surprise surprise. He was also a racist, and went on at great length about the importance of (as he put it) "blue-eyed music".

On the positive side, his piano solos are well worth investigating. My favourite is an unjustly-neglected setting of one of the Irish reels collected by Stanford (name escapes me, minor key - not Molly On The Shore, which is pretty well known). It would make a great recital piece because it's quite dramatic, fairly difficult, and not too long. I have a recording somewhere of pieces played from piano rolls which he had made himself, and fell in love with it. He didn't like calling the instrument a piano, however, and renamed it something like hammer-box-string.

You're right, a fascinating character.