Can't argue with any one of those 13 points, Jim.
13? I'd include 'respect by the audience for the song.' To whit, if someone sings the line 'and the ring from off her finger, she instantly drew,' it shouldn't be the cue for the entire kindergarten to put their fingers in their mouths and go 'pop'. Or, in the John Tams 'Rolling Home', to have the line '..and let the toast go free', always followed by an inane cry of 'Free toast!'.
Maybe I'm being an old fart, but sometimes we should listen to the songs afresh instead of taking them for granted.
And did you mention 'proficient singing', Jim?
And can I come to any session you're thinking of organising? I'm in West Wales, so it's only a short paddle from here...(they do say that, Pict-wise, the Welsh are only the Irish that couldn't swim!)