Remodeling the articulated bus – question for registration

Hello everybody, I’m new here and also relatively ignorant in the field of truck & utility vehicles. So please forgive me for the one or other “dumb” question. It’s about the following, I want to buy a articulated bus and rebuild it. Is it meant: sit out, except on the driver’s seat, partially darken windows and convert parts of the windows so that you can take them out and put them back in again. After that you should still be allowed to drive on public roads with the bus. Now we come to all the questions: Can I then register the bus as a truck? How can I get away with the registration / insurance most advantageously? If the seats are outside then I need a passenger transport ticket or a “normal” truck driver’s license? Questions about questions. I thank you already once for the answers Greeting Dennis