Fairly straight forward.
Case study will be a case study. Use common sense and business acumen
Define the problems
Back up recommendation
They normally leave the room for 20 minutes whilst you make notes etc. It's not rocket science. Don't use the obvious GCSE type models like SWOT.
It might be around a bank which as some trouble due to a merger, highlight the problems. Highlight quick wins for the client and Accenture, think about critical success factors. If its a listed company whom are you accountable to,
Then they will most likely go through your CV,
HR interview simple, how much you get paid, reasons for leaving, some competency based stuff -with them being HR they are quite stiff, The main person you have to build a rapport with is the MD.
I'v heard at time the MD doesn't even want to go through the case study he just wants to talk, be personable, ask questions., find common ground.