The chances of Iran agreeing to the preconditions, IMHO: Slim to none. Relax ;-)
I wouldn't rule that out. The Iranians are just dragging things out. They are rug merchants. I lived in Iran for a few years and know how they negotiate. They like to take you right up to concluding a deal and then change the conditions at the last minute in hopes that your eagerness to stike a deal will result in some last minute concessions.