The 20NET is the SRI Turbo, the VXR is the 28NET 2.8 V6 Turbo (its an alloy engine as well)
Exhaust and Turbo - Yes
Inlet and injectors - Yes
If you can get your ecu live mapped then you shouldn't need to swap looms BUT isn't your ecu the YH with a Z22SE map on it? which isn't the same make ecu so could be a little more tricky then the Vectra B/ Astra G ecu
Yeah big cooler
Also it might be an idea to run the NET/B207 cams as your cams will have too much overlap (although it might still work)
If you swapped the cams you would either have to use the brake pump on the exhaust cam or cut the cam and blank it off!