Can anyone recommend MP3 filing SW that will let you add/name fields (for example, fields like: tempo, mood, energy, etc... ). Is there one that will display in table-"excel spread sheet"-rows/columns?

I think Mp3Tag is what you're looking for. It lets you add custom fields, and also displays tags in columns that you can directly edit.

The GodFather might be able to do it as well, but I can't check at the moment to make sure. This has been my favorite tagging application for a long time now, but foobar2000 0.9, which meets all my current needs, came out around the time of my last format and so I haven't reinstalled The GodFather yet.

http://users.otenet.gr/~jtcliper/tgf/