Lucky you!
I'd better admit that mine's only on order. ... But scheduled to be built on Monday! So

The price included electrics.
My current car has roof bars and I put the bikes on top. Works ok but it really hits the fuel consumption (not such an issue on the gtd!) plus my wife can't take the bikes on her own. Towbar mount is easy to use (once it's on) and shouldn't have so much effect on the air flow. ... I'm doing a good job of convincing myself.
Don't bother with a strap-on rack if you can avoid it. Far too flimsy
...plus I can buy a caravan...