Yes, there are lots of standalone EM options, no you dont NEED standalone and perfect power will work fine, but a standalone will be better, but also requires lots more programing and tuning.
What rallitek does w/ perfect power, is instead of upgrading the injectors they add a 5th injector right in front of the throttle body/intake and all the extra fuel the turbo needs will be supplied by this injector when boost kicks in, and Perfect Power can control that 5th injector.
I dont think you'll need higher flowing fuel pump and wrx injectors, but talk to rallitek in a week (they are gone for SEMA now) and they should be able to help out. The 5th injector boss and everything for that are also on their website.
*Also* instead of an intercooler you could use water injection.