For a bit of FACTUAL help here
YES, NZ still has a BGT exam requirement, as does PNG these days as their regs are based on the NZ ones...
Was someone seriously suggesting a special endorsement was not required for a C208?! I don't think so. Differences between single engine turbines and single pistons are rather extensive to say the least.
Best theory books to hit up for turbine theory would be:
- The Jet Engine (by Rolls Royce)
- Aircraft Gas Turbine Powerplants (by Jeppessen)
Very useful books and important to wrap one's head around the theory of jet engines - if you stuff up they are a heck of a lot more expensive to fix...
Look up the NZ CAA website and find the syllabus for the BGT exam and it will give you a good idea of what areas are good to study!