getUnitCombatType

Where in the world is this function actually defined? I can find a tonne of references/calls to it, but the function itself eludes me...

All these functions are defined in the sdk. Your python code is calling C++ functions. If you need to know what happens inside those functions, you can look inside sdk files like Cy*Interface.cpp. Your particular function is defined in CyUnitInterface1.cpp.

Ah, cool, thanks.

The online Python API may help here, too.