Question

Have a good week! 
1- From the standpoint of international laws of war, one must distinguish between harming civilians and harming soldiers (although a civilian loses that protection when he takes part in the fighting). I would like to argue that when fighting a culture which by its very nature does not accept this morality, and which educates, for example, that every Jew is a devil, then one need not treat them with the caution required by the law. (Of course, morality always obligates caution in killing, but the law is at least somewhat positivist and not based on natural morality, and therefore morality must be judged case by case.) So although it is not the fault of all the civilians for the education they received, are we nevertheless obligated to treat them that way?
Please note that I am not making a legal claim about the protection to which civilians are entitled when a terror organization uses them, but rather that the law itself does not apply to them at all (and only ordinary morality does)?
2- I would also like to ask: how much collateral damage does the moral and Torah principle of “if someone comes to kill you, rise early to kill him first” allow? If, for example, we know that a terrorist is about to bomb an entire city with a nuclear weapon and there is no time to find him, would it be permitted to quickly bomb an entire country of innocent people when that is the only way to prevent it and neutralize the bombing?
That is, is it considered that the defenders are killing the others and we only need to ask whether that is justified, or is responsibility for their deaths on the terrorist, while the act of defense is not considered an act of murder?
3- What does the Rabbi think about the common left-wing claim that if more people died in Gaza, that proves that we are not moral? In other words, justice is determined by the amount of suffering. 
Thank you very much!