How do you calculate how many troops the main villains can counter attack with?
That doesn’t change. There is a randomized formula taking into account the population size, the villain, etc.
Are they going to get a population boost when revisited after a long while?
Good point. I need to make immigration happen when the site is in a ‘frozen’ state. I think I’ll have the clocks ticking for a little bit after attacks so they can heal up, etc.