You can Export RAW shots from Aperture... Export MASTER exports the RAW file.
Personally, i dont understand why you would want to do this though. I import all my RAW shots into Aperture 2.1 sort and process them, then export TIFFs into PSCS3 for final touch-ups, but, i dont do enough in PSCS3 to warranty needing a RAW image, Aperture take care of 99% of the processing, CS3 is basically just used for cloning dust bunnies. I feel RAW is only beneficial when making fundamental changes to the photo, like altering Exposure and White Balance, which should really be done within Aperture anyway.
As for Files Everywhere, Apertures single Library file solution for this is very good... as long as you keep it backed regularly obviously, as its all your eggs in 1 basket otherwise.