Do I need these? How do I get them?
Musicbrainz Username and Acoustic ID Key
You don’t need them for fixing your songs but you do need them for submitting data back to http://musicbrainz.org and http://acoustid.org. Submitting data improves the quality of these community databases and improves the accuracy of Jaikoz and SongKong tagging for others.
You can submit pairings between Musicbrainz and Acoustid, which says this Acoustid maps to this Musicbrainz recording. You can also submit barcodes, ratings and genres automatically.
You can also store a list of the Music you own on MusicBrainz and optionally share it with others, this is called a collection.
You can register for totally free usernames/keys for both these sites from their websites, there is no charge. However in Jaikoz 5.2.0 hopefully to be released today you no longer need to create an Acoustid ID key Jaikoz can automatically generate one for you.