I've finally got Microsoft Visual Studio installed again, and the OP API set up, after I lost everything in a fatal hard drive crash (including all my source code).
Thanks to FireSoul for his build environment, made the process much easier with missing files from the API.
Studies permitting, hopefully I'll have some new missions shortly. Currently, I've only installed the SFC2 OP API, but will be looking to install the SFC3 API as well, once I've done a few OP missions and recreated the ones I lost, including the Doomsday Machine mission.