I did a search for Performance moddifications for Teslas and came up with:
https://unpluggedperformance.com/
Looks like cosmetic, suspension, and brakes, just as you suspected.
My VIN was available several weeks before my build date. From what I've seen it is normal to have the VIN long before the build date. But I don't know what it means if you don't. Best bet is to reach out to Deysha and the others that monitor that account.
I don't think COTUS is working for anyone with 2017's yet. (Correct me if I'm wrong anyone who has gotten it to work). So you may never be able to monitor progress yourself.