Regarding arranger parts editing or style creating.... I found no way to enter a pattern edit screen, it seems the only editing functions are those provided by the Arranger View, where you can change only sounds or loops for the styles. Since the majority of the styles are using live drum loops, the midi drum part is not programmed on them, so if you assign a midi drumkit to them you do not hear any drum sounding...
On the G70 I like to play with make up tools to modify the style and you can get a totally different sounding style just changing the drumkit for example....