yes, you need all the wiring, pass side motor mount, duratec trans ( i think), wiring harness, ecu.. radiator probably .. etc.. not too hard, you will basically have to take EVERYTHING off the zetec car and then put the duratec stuff in.
It's only worth it if you have a donor Duratec car. End of story. I am almost fed up with my swap. I started with a zetec car with no motor. I bought eng, trans, and all the fixins... The engine is all bolted in, but now after a month and a half of trying to piece together wiring, I'm going to rip the entire wire loom out and install one from a dura. car.
I really like all the Cosworth things for the Duratec, but I also like the Powerworks SC for the Zetec, just need to built up the bottom end so I can get the stage 2 with 15psi and save a few grand for the kit it's self.