Depends a bit on the level you are aiming for. If it's a small single-engine operator the questions will be quite different to those asked to be CP of a turbine commuter airline.
Generic to all levels:
- The relationship of the Civil Aviation Act, CAR, CAO, CASR, CAAP and AIP (compared with the clarity of the NZ regulations, a right clusterf...k)
- Powers vested in CASA
- Responsibilities and accountability of a Chief Pilot
- Recurrent proficiency checks required
- Flying and instrument recency requirements
- Facilities that the operator must provide
- Maintenance certification allowed by pilots, MEL use etc
- What's in your company suite of manuals (they will grill you on this, so you'd better be able to quote or at least quickly access whatever obscure information they ask for)
- How your SMS functions in practice
- How your fatigue management system functions (if you have one); also wise to know CAO 48 or the 'standard exemption' backwards
Additionally for a bugsmasher operation they should give you a flight planning exercise and a weight and balance to complete. For a larger operation they will want to check that you understand the performance regulations and limitations, EDTO etc. Don't be surprised if they want to run a flight test or simulator check.
At this stage each regional CASA office seems to play it to their own preferences, but I believe that they are making some effort now to standardize.