Tzu
Regarding your query on 'delivery'. You are probably correct. Taking down someone's songs with just a pencil and a notebook inevitably misses out on a whole host of factors some of which you flag up. The answer, like much of the rest of the subject, is we don't know.

.....until Grainger came along with his cylinder recorder which gave us at least more information, but even then the environment in which they were recorded has to be taken into account. What we have is a tune and a text and perhaps a little biographical info, and maybe an odd comment was taken down. Folksong collecting has almost always been an amateur occupation (with some notable exceptions he added hastily) and I for one am extremely grateful for what we have.

My great admiration for the works of Sharp, Hammond, Gardiner, Baring Gould, Kidson and others of that era, is that whatever they did with their editing it would appear that they tried their best to leave what they collected intact as recorded in their manuscripts.