1.  There is not an iota of technical proof as of current that Iran does have a nuclear armament programme. There were several points of evidence presented as such but subsequently negated.

That might be, but there are certainly indications pointing towards Iran wanting to conceal parts of their nuclear program and possibly aspiring to widen their program from civilian to military purposes:

Mohamed ElBaradei, head of the International Atomic Energy Agency, told diplomats that his inspectors had recently obtained documents from Tehran showing that the Iranians had been given various instructions on processing uranium hexafluoride gas and casting and enriching uranium. These had been obtained via the black market in nuclear technology headed by the disgraced Pakistani scientist, Abdul Qadeer Khan.

Informed diplomats said the blueprint for casting uranium was required in making the core of a nuclear warhead, although that alone was not enough for the manufacture of a weapon.

And

The story dates back to the Clinton administration and February 2000, when one frightened Russian scientist walked Vienna's winter streets. The Russian had good reason to be afraid. He was walking around Vienna with blueprints for a nuclear bomb.

To be precise, he was carrying technical designs for a TBA 480 high-voltage block, otherwise known as a "firing set", for a Russian-designed nuclear weapon. He held in his hands the knowledge needed to create a perfect implosion that could trigger a nuclear chain reaction inside a small spherical core. It was one of the greatest engineering secrets in the world, providing the solution to one of a handful of problems that separated nuclear powers such as the United States and Russia from rogue countries such as Iran that were desperate to join the nuclear club but had so far fallen short.

The Russian, who had defected to the US years earlier, still couldn't believe the orders he had received from CIA headquarters. The CIA had given him the nuclear blueprints and then sent him to Vienna to sell them - or simply give them - to the Iranian representatives to the International Atomic Energy Agency (IAEA).

Iran has spent nearly 20 years trying to develop nuclear weapons, and in the process has created a strong base of sophisticated scientists knowledgeable enough to spot flaws in nuclear blueprints. Tehran also obtained nuclear blueprints from the network of Pakistani scientist Abdul Qadeer Khan, and so already had workable blueprints against which to compare the designs obtained from the CIA. Nuclear experts say that they would thus be able to extract valuable information from the blueprints while ignoring the flaws.

"If [the flaw] is bad enough," warned a nuclear weapons expert with the IAEA, "they will find it quite quickly. That would be my fear."

Both quotes above points in the same direction, although I really don't know what to make of the alleged CIA covert operation dubbed "Operation Merlin". If true, a rather hazardous and irresponsible operation in my opinion, but it seemingly points to the fact that the Iranian regime were willing to pay/acquire more knowledge on how to develop nuclear weapons.  The fact that the Mujahedin-e-Khalq disclosed the existence of nuclear sites, a uranium enrichment facility in Natanz and a heavy water facility in Arak, in 2002, unknown to the IAEA, doesn't add to the reliability of the regime, when propagating their peaceful intentions.

If, in theory, Iran does want nukes, the motivation is what the PNAC seems to have acknowledged (see Migeru's quotes): deterrence, not threat. Threat makes no sense when you have a few nukes, and delivery systems that will instantly identify you as the sender, but your opponent has hundreds (Israel) or thousands (USA) of nukes for a counterstrike to eradicate your entire country. On the other hand, since both Israel and the USA do openly threaten Iran militarily, and the USA 'encircled' Iran from all sides, deterrence does very much make sense.

I would say both deterrence and threat.  Deterrence against the US and possibly Israel and posing a possible threat to the neighbouring regimes and even the possibility of extending their influence into Iraq, Lebanon and some of the Gulf States under the nuclear umbrella, which could lead to a possible arms race in the region.  

(.....)But the main obstacle to stopping the spread of nukes is the hypocritical love of nukes by existing nuclear powers (including France, hint hint). As long as they don't show any inclination to plan to dismantle their arsenal (which would be their obligation under the nuclear non-proliferation treaty, BTW), others will have a motivation to get ones themselves.

Yes, I do agree that the lack of nuclear disarmament is an obstacle to the non-proliferation of nuclear weapons, but according to the first article of the NPT, the first priority seems to be the issue of non-proliferation.  This because if disarmament was the priority then a dozens of new countries would be nuclear powers before we had finished disarming just a few, and the disarmament would have been for nothing.  

Even so, I do find many of your points intriguing and being quite plausible reasons for the seemingly defiant mood of the Iranian regime.

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