Frank, couldn't disagree more - sorry.
The English language song tradition is basically a narrative one, the role of the singer being that of storyteller - we've been told this by every source singer we've ever interviewed. Use any voice other than your own natural one and you are telling your story in a 'funny voice', the way many revival storytellers do. Unless there is something physically at fault, the tonal range of the natural voice is quite capable, when developed, of taking in all the emotions. 'Enhancing' a song with head voice is, IMO a theatrical device which has no real place in the singing of traditional songs.
Similarly with breathing. Listen to most of the field recordings and unless a singer has lost breath control through age or infirmity, he or she will take a short breath with a comma, slightly longer with a semi-colon.... etc - as you would if you were narrating rather than singing, otherwise I believe you are substituting technique for interpretation.
Jm Carroll