Would Iran threaten to USE a nuclear bomb, and/or merely just go ahead do it?
Will they stop at creating ONE single nuclear device?
For the last 35 years the Iranian Isalimic regime and its Revolutionary Guard has become more and more fanatic as time goes on. During the Iran - Iraq war, the Iranian government had no shame by sending children on bicycles across minefields. During that instance approximately 5,000 died. Life magazine had a picture of the goings on. If I remember correctly, the Iraqi soldiers looked on in disbelief.
So to answer the first part of question 1 No and the second part of question 1 Yes.
I would surmise that they would not stop at just makling one device.