On the upload problem -- looks like I missed a directory or something when I packaged up the mp3 libraries... You can download them from
http://www-users.rwth-aachen.de/jens.vonderheide/software/java_id3.html

I'll check out the discovery thing ... The NPE is actually correct, because your machine doesn't properly respond to the broadcast. However, it should proceed on to then discover the empeg.