Hi!Hank asked above whether the 6 minute unaccompanied song was done in one take, saying it would be difficult to memorize the words. The answer is "yes." Simple answer, more interesting question.
Once you've learned it, it's relatively easy to sing a long ballad from memory. It is a story song, after all, and has a definite sequence of events to be followed. I can pretty much sing a "big" ballads from memory even if I haven't done so within a year provided I am not tired or distracted. Much more difficult would be to sing a long lyric song with no plot line to keep the memory straight.
On the technical side, it's much easier to "punch in" a word, a line or a verse of an accompanied song when there's been a flub because there's always the instrumental track to keep the attention of the listener. With solo unaccompanied singing, every breath is audible because that voice is the only thing happening.
As far as keeping on pitch is concerned, any of the Irish Mudcatters can tell you that's something that comes with practice and self-confidence... not to forget having the right key to start.
Thank you, Earl and everyone else, for your kind encouragement.
All the best,
Dan