Yes, uforadiant.exe is correct.
I'm not positive as I don't do mapping, but I think you want the main engine path to be the top UFO AI directory where the game is installed, and the compiler binary to be "ufo2map.exe"
Mattn or one of the coders could probably clarify better than I could, as well as tell you what map-work is needed the most.
Edit: We also have a "mapping" section in this forum, I'd ask more questions there.