Gould, top of page 59: "Unless conditions are cramped, [unison] notes of different duration take a dot beside each notehead" - so I'd say LilyPond is wrong here.(a) Is the Lilypond default presentation really the better way of indicating this? If so, I can just leave it alone. Otherwise,Yes it is, AFAIK (See E. Gould as ref. as far as I remember)
Paul