I was using TagScanner on Windows. Since it's not available on Mac, I tried TriTag, and while it has the right idea, it's just too basic. I want to be able to mass rename: artists, track, GENRE, COMMENT SECTION, AND COMPOSER SECTION. I stress those last 3 attributes because none of these Mac renamers seem to offer this.

I'd try iTunes, but does iTunes let you (1) rename the file based on your id3 tag specifications and (2) permanently save album artwork to the MP3 file itself?