What competences should a Windows driver developer have?

I work for a small company developing a USB device controller for VR applications. We are at the stage of development where we would require a software developer to work full time on Windows drivers, user interface for device setting, and Steam integration. Since no one in my team has any in-depth knowledge of PC programming, I was wondering if anyone here might help me determine the skills that such a developer would require.

So far I have managed to scrap out that a good knowledge of WDK is required with experience of writing Windows kernel-level code and extensions. C and C++ languages are required to work with those. What else am I missing?