I'll try and answer these for you...
1.The PSR-3000 will allow up to 32 bars in each style section...the more bars used,the larger the style size will become and it will take up more space in the user/card storage area.
2.The Style Creator is onboard the PSR-3000.I use it to take parts from one style and use them in another(Assembly)which is the easiest form of editing but still will give great results.
3."Groove & Dynamics will change a swing to an 8 beat,or an 8 beat to a swing.You can change 8 beat to 16 beat.You can change an English Waltz to a Swing Waltz.
Groove & Dynamics can affect one style part or any number of parts.
4.Styles can be from approximately 12 KB(a basic piano style) to 32 KB or larger,depending on the number of parts used and their complexity.

I hope this helps.

Ian

The answer would be if an arranger which would vary a style as per BAND IN A BOX does, it takes style elements from a data base but does this at random depending on the chord type.
As Boo knows I have been and still am a Korg & Roland fan, at the moment I use a PSR3000.
Another BIAB feature that arranger could use is the SOLO Around the Melody feature which really bring the thing to life.

tnx ian, much appreciated!

Craig,
Yamaha tried a similar idea with the PSR-8000/730 using what they called a "Virtual Arranger".
Here is a quote from the introduction of the PSR-8000...

"'Virtual Arranger', a new innovation from Yamaha, adds more than a simple variation of style the user plays. It will add riffs, phrases, chord changes, and other embellishments appropriate for that style, making users sound even more professional."

In practice,I found it worked fine for very simple chords,but once you started adding Maj7th, 6th or 9th chords,the results weren't all that great.
BIAB apparently handles this stuff better,but it is not a "live" player.
It would be nice to see the Yamaha implement BIAB's idea but allow real time playing...

Ian