What is required to install these on a 2004 STi? Do they come with everything needed? How do they compare to the APS fuel rails? Lastly, which Aeromotive FPR would be a good choice?

Contemplating Fuel Rails for the below mods which I already have in my basement to be installed:
FPGreen 8cm 3"
NISMO 740s's
TGV deletes
APS turbo inlet
APS header
Snow Meth Kit
APS DR525 FMIC
Turbo-back

Buy some race gas instead of the fuel rails and regulator. Your green will thank you for it. :) 740s should be good enough for the green with no rails or regulator.

What EM are you using?

no race gas - running the snow meth kit. Agile will ProTune :)

Your rails will be just fine. I would save the money for something else