1)sure, taking the fight to them seems reasonable, as long as your willing to kill those uninvolved overseas on foreign soil. You would be placing your shoes on those in other countries who will want to defend their homes, meaning you'd have to kill civilians who rise up against you cause they see you as an invader.
2) The people in that vicinity who are gun owners will have an interest to defend their homes and businesses quite fiercely as its their homes and livelihoods, do you think that they would simply flee? I guarantee you that many people in Florida would travel to defend the region if an invasion occurred as they would think that they were next if they didn't stop the invaders.
3) unity is not as important as freedom. Also Yeah, if our lands were under threat I would volunteer if I thought we were in danger, its this thing called altruism, and I practice it frequently even if I get screwed over in the end.
4)I work a 2-10 job as a janitor and im not going to college, I graduated high school a few years ago and I will be 20 in a few weeks.