I heard that carbon fiber roof was for the e93 M3 to make it lighter than the aluminum based regular e93 three piece roof.
I thought M3 coupes came out before the sedan. The only time there has been a US spec M3 other than a coupe was the e36. The e36 M3 coupe was from '95-'99, sedan from '97-'98 and the convertible from '98-'99. But who's to say history will be a predictor in this case.
It will be an exciting couple months if they release all these new models so close to one another. Especially since we have been waiting almost a year since the e90 release to get official e92 information.