Yeah, I think you need the 12.12.0 cable for this.
As for the mirror dip, I don´t really know, the only person I know here with an MK3 Leon has another FR so I couldn't say.
I dont think its a VCDS version issue. My hunch is that its to do with the production dates of the cars. The carbon fiber look is probably to do with the Cupra, as is the lap timer. Maybe earlier versions of the firmware on the in car systems dont contain those images/features.
I've tried it with mine, and enabling the lap timer doesn't show, and changing the background seems to make a small alteration to the font, but no carbon fiber look.
One thing that I have read is that as part of the service schedule, they commit to ensuring you have the latest software on the car, I'm trying to find where I've seen this, but I know I've seen it somewhere. Maybe they may come along with "bug fixes" like the reversing mirror not returning to its normal position all the time.