I'm trying to have one of my menu buttons use a shortcut key for me to use,
but aside from the main ones in the standard menu toolbar [File, Edit, View,
Insert...], I don't know how to quickly recognize what shortcut keys are
already in use.

Is there a way to do this... to find out what shortcut keys are already in
use?

If I had more time I would search through these posts but I have to get some
things finished quickly, so am hoping that someone will be able to share some
knowledge today or tomorrow [or whenever, I'm not too picky on being helped].

Any help would be very much appreciated.
thank you.