Regarding automation:
It it possible to use the circuit network to order missile strikes. Just input the X, Y and L (Launch) Signals and the missile starts.
If I remember correctly there are some mods that can output coordinates of entities like biter spawners (AAI Signals maybe?).
Wasting ammo should never be a problem. You can access the contents of the payload chest with the circuit network and just load a single atomic bomb (or whatever you choose). The modular payload system is also the reason why I can't display the area of impact. There are so many modded ammo items that behave completely different - this makes guessing the explosion radius practically impossible.
Own ammunition for this mod also has no practical use. I could add a special nuclear-warhead item but it would have almost the same recipe as an atomic bomb and behave similar.
Nevertheless I hope this was helpful.