I do not think that the Iranian government would proactively attack Israel with nuclear weapons. I don't think that there's a particulary great risk of terrorists getting their hands on fissionable material as long as Iran stays stable, nor do I think the Iranians would supply them voluntarily- it would be easily traced back to them and would have almost the same backlash as trying to nuke Tel Aviv.

The chief reason why Iran would want nukes is as an insurance against any other middle eastern adventures by the USA and Britain. I don't like the Iranian regime or the idea of them having nuclear weapons, but a preemtive strike isn't worth it IMO- unlike North Korea, wich ideally I'd like to see getting stomped.

Iran's rethoric about the US being the great satan or wanting to destroy Israel does not originate from a whim of the Ayatollahs deciding that they wanted to piss of the world for no good reason. Acknowledging them won't turn them into a bastion of liberty and tolerance but will accomplish a lot more than delivering suggestive and ultimately empty threats. If I'm not mistaken, Iran will have another presidential election this year, wich should be interesting.