Me thinks you're on the wrong track, sir. The only missing parts to adding a side I could find are:
EVA graphic controls (so the new side has new eva - though I swear I saw it in there earlier, I'll look again)
Definition for ParadropSpecial (the ol' prefix = side name won't work for that) but I think there can be a way around that. Tech Airports are too nice to remove all together.
A few other small details, but as far as getting the game to play the new side correctly, if human, seems to fall right under the defaults posted at the end of all .map files for the YuriCountry stuff, since they're just the defaults anyway they shouldn't really need the extra data, but if they do it can always be added.
Buildings, building, and what the build? Isn't the sidebar interface the same for all? Why would that need changed?