If Israel would do that, they'd risk a war against most of the Arab nations.
Bushher was intended as a civil reactor and in planning for 30 years. With the Russians, they'll get civil reactor tech, and have to use Russian fuel rods, that are returned to Russia when depleted. That is or was the plan, at least.
Iran does or did have enrichment facilities for uranium, b/c they're necessary for some types of power plants, but they can also be used for military purposes.
Inner-politically, Iran has to present itself as a modern country, and hence it looks bad inner-politically if Iran is denied modern technology.
The current situation was mainly the reason of lobbying by the US.
I think that anyone in Iran knows that if they'd ever attack another country using a nuke, they'd get countless nukes back.
If the Muslims wanted to nuke Israel, they could use Pakistan instead of Iran, b/c Pakistan already has nukes, and there are plenty of Muslims w/ political influence in Pakistan.
Iran is not fully democratic b/c of the influence of the Islam in particular government functions. But still, I doubt they are that crazy to want their own country destroyed. They certainly don't want to turn all their people into martyrs, do they.