Re: The last two lines in the song. (I'll use the slash before the vowels for the fada.)
The version in Irisleabhair na Gaedhilge is

"N/i'lir f/os n/a n/i bheir go deo agam,
You aren't yet and you never will be mine,

Mar do b'fhearr f/i dh/o liom mo bhuachaill deas."
For I'd prefer twice over my handsome boy.

The "buachaill deas" I take to be the same as "an buachaill caol dubh"
of another song, "the spirit of drink". I suppose a cowherd sticks to the cow in all weathers and situations, just as alcohol sticks to the addicted. I guess the last line means "I'd rather stick with the booze." It's likely been replaced by the line in English because people would take it too literally.