Wow i made someone who dont like Clicker/Idle game to enjoy this game! you made me so happy ^_^
Awesome feedback! and i agree with everything you said, will do for sure in future updates for the full release!
The original idea of the countries was to be able to attack only the ones you share borders with and you fight you AP with theirs, meaning you can always attack but you will have less chances in wining and invading if you AP is less than their AP, also the countries AP will progress (just like they are real players) and there progress is depending on their size.
but as you know all these complexity was little bit hard to achieve for the game jam but hopefully it will see the light in the full release.