I dont think Tesla will use carbon fiber again in the near future.
I believe any cars on the Bluestar platform will be made out of the same material.
I think that any cars on the platform will share as many body panels and stampings as possible. Perhaps cosmetic shapes will be different, but all the pieces that contribute to structure and wheelbase will be the same.
There is no reason to think they would offer a car with 2 motors. Their core expertise is in the motor, PEM and battery, so I would expect them to be able to offer more powerful versions of any/all of those ( whichever is the weak link ) to achieve greater performance.
I would love to see a car with 2 motors - one for each rear wheel, so that a differential is not necessary, but I am not holding my breath.