build slot isn't confirmed, although they are getting between 1-2 cars a month starting August, and i'm number 9 on the list, i didn't bother with any options / colors at this stage as its still ages away from needing to be locked in, but am thinking something different than black, all the other cars are and or have been black.
i read up on the whole bucket seat issue, and appears that it doesn't fit everyone very well, so may consider going with the adaptive at half the price.
The CCB on the C63s is only 9k (i didn't get them) but that's for the front only, i think the GT4 is front and back, reading on this it "appears" that the standard brakes are more than enough given the weight and balance of the car.
With the alcantara i was referring to the extended bits, dash, doors etc...
apparently W Rohrl is also getting one, out of curiosity have you ever come across his specs??