In a RIP app like Command Work Station, you have to do it on a job by job basis. That being said, our Xerox trainer said it's best to let the paper come out face down, by he didn't explain why. They must default to that for a reason. I understand it's better to run face up with heavier stocks or NCR.
I am not sure what "postscript kid" is... I know there is a verison with "internal/bundled" EFI Fiery RIP and with external EFI Fiery RIP or external Xerox Freeflow. I guess we are talking about the first option; I do not think a printer this fast could work without powerful enough RIP.
All the Fiery RIPs, whether internal or external, can be managed via the Fiery Command Workstation; and all printers can usuall be managed through a web interface.
In the CWS log as Administrator and then go to Device Centre (click the tab with this name) and look to the bottom right corner - there is a button "Configure"; by clicking on it a new window opens (for it to work correctly, Java needs to be installed and running), here go to the section PDL > PS, there is an option "Output delivery" where you can set up how you want your output to be delivered...
Where there is no "visible" RIP, access the web interface by inputting printer's IP adress in the address line of a web browser; some things may be configured here; and again (at least with xerox machines) look to the bottom right corner, there should be a link to further machine configuration.
It is true that by default the pages are output face down, which i doubt anyone welcomes... and the "security" reason is rather funny, although in an office environment it could actually make some sense (so that a passer-by cannot glimpse what is being printed...).