2. Macros make the parsed grammar dynamic. Usually compiler has hard-coded parser generated by LALR parser generator(like Happy or Yacc) compiled in. Introducing each macro like you proposed would need(I think) generating new parser(at least for the fragment of the grammar).

Dylan has macros and a syntax more interesting than LISP's, so perhaps it would be worth looking at how they handle it. I forget now, but I don't think it was too difficult. I also considered some of the issues we're discussing in an unpublished paper that appears on my publications page, http://www.cl.cam.ac.uk/~kw217/research/papers.html#Wansbrough99:Macros (Section 8 looks briefly at Dylan-style macro facilities). --KW 8-)