Good point. There's nothing in any law that says a constitutional convention could be limited to a pre-approved agenda, so that route for changing the Constitution would most likely result in the destruction of the Constitution.I vote a concrete NO. What it does show is that it can/will be changed which opens the door to tyranny.
NO.
As for state ratifications, I don't think it could be done.
Be that as it may, you have a good point.