If you have the XGRA instruction manual, all the music credits are on the last pages. They're probably in the in-game credits, too. I ain't typing them out if you have access to that.
The music in XG3 was done by the
Ministry of Sound. The artist of each song is on the loading screen at the start of each track, and the site has a list of all the artists so you can probably find their stuff. I don't know the song titles for each song (except that the song in Atrodaitoshi is called "Hey DJ!" I think), but they are probably in the game credits, too.
Hope that helps.