Where is the best place for a C# developer to get started?

Having a project is a great way to start development! The powershell community here is very active, is that an option over C? That said, the best way to start is to get comfortable with basic development skills. You can do that simultaneously with building your automation scripts, but make sure to test, test, and test again before hitting production.

For the API itself, we released an article series last summer on getting started with iControl, complete with samples in several languages for each task (not C unfortunately) for the SOAP and REST interfaces, but I'd recommend you focus on the REST interface since this is a new effort. Seeing how each language handles the basics will be helpful in applying to C.

There are many C examples in the codeshare, Maybe the best way to get started is to take those samples (which are most likely all SOAP-based) and turn them into REST-based samples. There are many here who can help you along the way, but I'd encourage you to get started and ask questions once you have some sample code for us to look at.