Yes, so long as you are actually going to FIGHT to cause the change you want. Declaring war with a understanding that the armies will never meet and that no looting or anything will be done, that is wrong.
Eh, I don't know.
Placing a standing kill order on all neighbors, but never actually invading them, doesn't seem un-SMA to me. Declaring war for the purpose of auto-engaging any errant neighbor seems like a lot of fun. Way more fun than sitting at neutral would be. That is to say, I would see nothing wrong with two realms basically deciding they find it intolerable to have the other realm's nobles or soldiers ever enter their land, and thus declaring war, even if they have no intention of conquest. War could be plausibly and SMAly declared with defensive aims.
