Asked about it at work, because I test drove one....a 645CiC with SMG.
1) The fixed hardtop is coming. Not avaiable yet, but coming. I specifically made sure they knew what I was talking about because we had a Z4 Convertible that HAD the fixed hardtop IN, but not installed....sitting next to the Z4 Convertible...so yeah I made sure they understood what I was asking.
2) No M/Performance package....but the 6ers have a sports package....ones with 19s. And the sales guy said you prolly could get a BMW spoiler...I liked SMG...if you consider that sporty...and it's an option included in the price of the 645CiC (i.e doesn't cost anything).
Active Steering with variable steering ratio
19 x 8.5 front, 19 x 9.0 rear Ellipsoid (Styling 121) cast alloy wheels, 245/40R-19 front, 275/35R-19 rear performance run-flat tires1,6
8-way power front sport seats with manual headrest and thigh support.
So yeah....that's what I found out from my end. Maybe it's different where you are.