Hey man! In my game i'm currently fighting like 15 spaceships so I havent gotten around to building these yet, but heres what i read in the patch notes.
"The Coordinated Military Command is now considered a district center. It will be further differentiated later, but basically the idea is that it's more of a "military district" whereas the civic center is more of a civil district."
So as of now, it's just an overpriced district center. Later, it will differentiate regions towards military or civilian if i understand.
As for placing district centers, I believe that it needs to be at least 3 regions away. So, if you control all the regions extending out to the 3rd region, slap down a teleporter, then see if you can start a new district. I'll play around more with it after this war I'm in