Hi Bernie,
Your best shot would be to go to biab forums, they used to be really helpful.

As for the styles, there are “midi styles “any songs you saved as midifiles could be played in the Pa4x like any other midifile you have.
The styles using real tracks would have to be saved as audio files.

I’ve never played around with audio on the Pa4x, guessing it plays mp3 files.
I’ve never had any luck saving biab files as mp3 ( could be something weird about my laptop) but have saved as wav file to be converted to mp3 using another program. Think I tried it for the pa3x.

Notation in the korg, haven’t tried it, I read my music from fake book or iPad. Biab does lead sheets, would have to do some checking.

Laptop doesn’t have to be as powerful as one would imagine. Check with pg. or the forum.
My 3 to 4 year old laptop runs them perfectly. I got talked into a laptop with a solid state drive. Big mistake only had 70 gigs, which ended up being nowhere big enough to fit the biab audio files. Hadn’t been using the program at the time, so didn’t take it into account.
Got around it though. Bought a 128 gig ssd external USB drive. Loaded the real track instruments on it. Worked well.

More recently I bought a tiny256 gig USB stick put everything on it and it seems to run just as well as it did on the external USB solid state drive.

I’ll probably get the ultra pack plus on usb hardrive , upgrade , 2017 or earlier, as I missed out on a couple of years of real tracks. Get a clean start and just add any extras that I’ve got ,back in.

From memory you can run the program from the drive with just a minor installation of some components into the computer, you can load the program into pc and use the real tracks from the USB drive, saving you from having to load about 100 gig of files into the computer, or you can load everything in if you have the space.