Regarding arenas the button activated stages aren't 'Publicly' released yet, best advice DL the latest Showdown file and delete the existing stages and replace accordingly with the updated code and textures :)
6.0 Will be beautiful and i will do my best to make it so :) as keson knows i have been in poor health atm and my mind isn't on task BUT i can say this game WILL have 30+ selectable arenas when im done