Wolfgang; Thanks very much for all the trouble & the interesting material. I was not aware of Huss. Something for me to brush up on.

Have you any knowledge if the song was transmitted orally?

a derogatory term for a catholic priest; don't you have such a word in English?

All I can think of right now is 'papist.' Of course that refers to all Catholics. Maybe 'papist priest.' I've never actually come across that phrase, though. Hmmm. Seems that in all of Scotish folksong there must be one.