It's very possible, but I can't do properly it inside the PA80, so unless something is different on the PA1x, likely you wont be able to do it either.
You'll need an external sequencer, any decent computer based app will do. Simply mute what you don't want in the original midfile and record the style data you do want into it.
On your second Q, there was an app that was available at Irish Acts in the download section that auto converts Yamaha stules to korg format. I used it with mixed results. Most times it worked well, other times the note tunings were off. In any case, I had to tweak an awful lot once I did the conversion ( voices, effects, panning, etc ).
AJ
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AJ