I think the hardest part is trying to work out where to put things once you have moved away from the basic minimal examples. I have had another play this morning and I think this would get me nearer to a basic template that would work for most things I'd look at. I'm using 2 \transpose but I don't see how to resolve that and I can't see how to come up with a macro that would change the 2 entries in one. Obviously I wouldn't always use all of this. I've left a "Kesh Jig" in.
Not sure of the chord shapes btw but I'm mostly open chords on guitar

\version "2.18.2"
  
  \header {
    title = "The Kesh Jig"
  }
  
  global = {
    \time 6/8
    \key d \major
    \tempo 4=100
  }
  
  
  melody =     \transpose g a {
      \relative d' {
      \global
      \repeat volta 2 {
        \partial8
        d8 | g4.^"~" g8 a b | a b a a b d | e d d g d d | e d b d b a \break
        g4.^"~" g8 a b | a b a a b d | e d d g d b | a g fis g4 } \break
      \repeat volta 2 {
        \partial8
        a8 | b4.^"~" d8 b d | e g e d b a | b4.^"~" d8 b g | a b a a g a | \break
        b a b d b d | e g e d b d | g fis g a g a | b g fis g4 }                 
      }
  }
  
  chordNames =   \transpose g g{
    \chordmode {
      \global
      d8 g2. d2. c4. g/b a:m d:7/fis
      g2. d2. a4.:m g d:7/fis g
      e:m g c g e:m g d2.:7
      e4.:m g c g c d:7 g
    }
    
  }
  
  words = \lyricmode {
    de dee di -- dly -- dee
  }
  
  text = \markup { \column{
    \line{ Other words go here}
    }
  }
  
  \score {
    <<
      \new ChordNames \chordNames
      \new FretBoards \chordNames
      \new Staff { \melody }
      \addlyrics { \words }
    >>
    \layout { }
    \midi { }
  }
  
  \text