Does X-Plane have an equivalent to SimConnect that can output data to a separate application (.exe) and, if so, is there any documentation available for a non-X-Plane user?

I don't know if this is equivalent, but maybe XPUIPC can help you:

 

http://www.tosi-online.de/XPUIPC/Home.html

 

It's the equivalent to FSUIPC.

Does X-Plane have an equivalent to SimConnect that can output data to a separate application (.exe) and, if so, is there any documentation available for a non-X-Plane user?

Use the Data Input & Output screen in X-Plane.

http://www.jefflewis.net/x-plane_engineering.html