Your biggest issue with the Vectra C ECU is the fact the entire Vectra C is controlled through a full CANBUS protocol. To swap this engine into anything other than a Vectra C, you'd be better off running the Vectra B Y26SE (2.6 V6) ECU, looms, transponder ring and key chips. It does work and I'm not sure if the ECU needs flashing or not, although I know with some Opel ECUs, engine capacity doesn't always matter too much when it comes to the ECU tuning. I know this as when I did the Z18XE swap into my old Corsa GSi, basically kept the 1.6's ECU in place and practically just slipped a 1.8 in. Even with the 1.8's injectors, it was still overfuelling a little, but it wasn't leaning out at all. CANBUS is a pain in the arse and not worth the effort. Using the Vectra B's ECU, from the same car get the transponder ring from around the ignition barrel and at least one chip from the key of the same vehicle. This way, you still have the factory immobiliser, but it will work without trying to bypass the security.
As for extras, with the Y26SE engine, it also uses a drive-by-wire throttle, but behind the accelerator pedal on the DBW throttle Vectra B (JR/JS model), is an accelerator pedal position sensor. Basically converts analog pedal signal into a digital signal for the throttle. Not hard to fabricate a bracket to attach the throttle cable to.
Also from the Y26SE, grab the intake manifold, rocker covers, throttle body, looms and sensors. They should all bolt to the Z32SE as they're the same block.