The long term agreements of negotiation are meaningless, US and Israel will break any agreement like clockwork, if not this admin, then the next. If Iran isn't stupid, it will restart nuclear research in secret when the dust settles, it's up to the other side to restart the war and bear the political cost.
Smartest thing is for Iran to delay as much as possible and then do everything possible to rush Chinese aid and disperse it around the country asap.
Iran doesn't dare to first strike US assets, so US will get it's assets ready either way.
No brain no pain. Since decapitating like half of their military high command has had no obvious effects I guess we can all draw conclusion.
The main variable here really is US political willingness to enter into a campaign against iran. Nothing the iranians could except surrender could really affect that calculus, unless Iran inflicts significant damage upon israel and scare off the americans from joining. As far as Israel goes, it is only deterred by strenght and negotiating honestly with either US or Israel is really only a show of weakness.
I don't think that's realistic. The entire Iranian grand strategy has failed, and their best option now is to swallow the bitter pill of the U.S. ultimatum and turn inward, with a focus on socioeconomic reforms and modernization.