You forgot #3 which is the most likely...
#3. Iran will get the bomb, make some empty threats and do nothing. And the reason Iran will do nothing is that if Iran uses a Bomb against Israel without justification either directly or by proxy (a terror group) they would be immediately blown to smithereens by Israels not-so-secret nuclear arsenal, the USA, Europe, and maybe even Russia or the Arabs.
Both the Isrealis, the US and even countries like France have promised Iran's immediate destruction if it used Nukes. Russia has always been rather paranoid when it comes to their security, and the idea of a nuclear-armed Islamic country near their borders (especially so close to Georgia) would make them very nervous. They have invaded countries on less pretext than that.
Ahmadinejab is not stupid or suicidal. He knows quite well that nuking Israel would bring about his own destruction. He gains nothing by it. Despite all his fiery rhethoric Ahmedinejad is a politician, no politician would put their country on a course that would result in their countries annilhation.
I wouldnt worry about Syria. Since Bush is gone, Syria has been trying to rebuild the relationship it had with Clinton and espicially Bush Sr. From Syria's standpoint, since its oil production in in decline it needs the US help more than it needs Iran's. Israel and Syria are having peace talks as we speak this week.