2) Nuclear weapons were an example. Of course I don't think I can have a nuclear weapon in my backyard. However, since the 2nd amendment itself is vague, it would not be unconstitutional to keep and bear arms. Arms being weapons. Nuclear weapons being, you know, weapons.
I suppose the amendment itself is vague. But having such weapons is unlawful, and if you got it to the Supreme Court, they would determine it to also be not protected by the Constitution.
So the second is really just as vague as every other amendment of the Bill of Rights. What constitutes a peaceable assembly? Local law defines it, and if you challenge that, then the Supreme Court will straighten things out.