Looking at the Clio V6 air con pipes shouldn't be too much of an issue.

Yes, I saw the Prius uses an electric compressor, relatively cheap too. But to keep things simple I think using standard Focus compressor should work ok.

Googled the loading of electric compressors, and some logical sense in my head.. every change of power conversion there will be some losses so makes sense to drive the pump directly off the engine, rather than loading the alternator more, to charge a battery, to then run the compressor