Hi @AnthonyCool, thanks for posting on the forum and welcome to the SimScale Community 
Regarding your questions:
- Please take a look at some of our turbomachinery tutorials, from there, you’ll have some templates to work with and set up your simulations
- You can leave the default k-omega SST option, it’s the best choice for most applications since it provides a good balance between the capture of near/far wall behavior
- For that, you can maybe check some of our validation cases (especially this one - even if it uses Multi-purpose, you can apply the concepts there to an Incompressible version). Retrieving an area average for the inlet/outlet is the best option for knowing the pressure drop in the turbine
Cheers
Igor