Yes, you could use a macro, but:
a) why do so when Word has the functionality of INCLUDETEXT fields built in;
b) that would be a lot more work to set up and maintain; and
b) who's going to maintain it?

As for the underlining & shading, that suggests:
a) something odd about your language settings; and
b) you have Word's field shading option set to 'when selected' (and the insertion point is in the field), or 'always'.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]