X12 StockSpec motors started shipping already, not sure at which distributor they're going to be available first tough!
As for the rotor question: physically all X12 Modified rotors do fit into X12 StockSpec as well, but in certain countries/clubs they may only allow the standard X12 StockSpec rotor (easily recognisable by black shaft and black magnet) due to size restrictions.
X11 rotors do not fit into any X12 motors tough, just to clarify that as well.