LW is able to differentiate b/w different file types. Be it music it'll categorise it as music, be it a picture (eg-jpg) it'll cat it as a pic, & so on. For mp3's you can add xtra info to them (id tag info) that'll help people locate them & know moe about the song. Yes LW can detect mp3 tag info & is effective when searching for mp3's; eg- the song's year, artist, song title, genre, album, track, comments, anything that's been added to to id tag.
However to search for a particular category of file then you should utilise LW's search options.