Dave Smith Instruments SYNTHESIZERS

I posted this on the Keyboard Forum, but these are kind of detailed 
questions and I believe there are a lot more subject matter experts 
here!  

I understand from reading the manual that once the Rack is slaved to 
the PEK, it becomes basically "set it and forget it." If a sound is 
edited and saved on the PEK, this automatically happens in the Rack 
at the same time (presuming they are both running the latest version 
of software). Here are my questions related to this:

1) In order to "sync" the sounds in both units, could I just go 
through and rewrite the programs (some or all) and this would sync 
them? Or is it easier to do some kind of sysex program dump using a 
PC? Would the PE Rack need to be upgraded to the newest software rev 
to support any of this? Where can I get the upgrade & how is it 
loaded? Lots of similar questions!  

2) If I use another keyboard MIDI'd to the PEK (with PEK chained to 
the PE Rack), will the controller fire all 8 voices, or just the 
PEK's 4 voices? I am assuming that the Poly Chain feature hopefully 
acts like a MIDI thru when this kind of setup is used. I would like 
to have my S90 serving as Master to do automatic patch changes on 
certain songs. I would mainly play the PEK's keyboard, but wanted to 
know if the S90 will indeed control all 8 of the voices when set up 
like this. To add another wrinkle to it, are there any conflicts 
when using Poly Chain to a PE Rack and MIDI thru to another keyboard 
altogether?

These may sound a bit "out there," but are questions that apply to 
my rig! Thanks in advance for any help you can provide on these.

Regards,
Eric