Sometimes the simple answer is the best though and the answer really is no....
To elaborate however, there are some mods to add countries, but these can cause issues ffrom simple log book issues to completely preventing you joining multiplayer servers unless you really know what you're doing...
Having AI aircraft made flyable is something that comes up over and over and there are mods to do this, but DCS updates almost always break it and this will also cause you headaches with multiplayer as well.
Further to that you're wanting to add additional aircraft that aren't readily available as flyable. Thus, unless you're an experienced modder with access to 3D modeling tools and willing to go through a lot of trial and error, and do it all over again every time ED release an update or patch, the answer as stated is no.