My pleasure, glad you liked it.

@Ente: Make sure you get in touch with them beforehand to arrange for the factory tour on Friday (provided that you arrive early enough). The factory is right next to the airport. Should be a 10 minutes taxi drive max. Our tour started at 11.30h. I don't know if there's was another starting later in the afternoon.

Regarding one car for two. I was in a group with only "single starters" so I can't really tell. However, as the other groups with double starters didn't have more time, I would imagine that you only get half the time for each. Except for the "free" track driving on Sunday afternoon, during which they let the second driver run with the second group while the first starts with group 1. So I would probably rent two cars if money is not the issue.

English instructions are indeed available. I was in a mixed group. Each group has two instructors. They split up the group during the briefings and gave instructions in German and English.