No they haven't, they've paid someone else to do it under their name. The new CRT rules could pave the way for the same application in motogp in the future, except that RedBull would be serious about winning and wouldn't do this unless CRT had proven to be genuinely competative/equal to the factory teams, which it could be in the future.
Simply speaking it would require RedBull to have an agreement where a chassis builder, like Kalex for example would build bikes and call them RedBulls. That's exactly what they have done in F1 and it isn't a new trick either, a long time ago there were formula one cars entered as John Player Specials, despite the fact that they are just a tobacco company. It isn't unfeasible of course that RB could set up all the infrastructure from scratch, poaching staff and expertise from elswhere in the sport or industry, it'd be the same deal though at the end of the day
That is simply not true. And that is not the way it works these days.
Adrian Newey is the magician behind the car/design, and he works for Red Bull. Just like Preziosi works for Ducati.
Red Bull designs their car in house. they own theyre own wind tunnel + autoclaves - vid here. - It is a full blown outfit. And definitely not a re-badging exercise.
I dont know where youve gotten the bunk info posted above, you may be confused with the torro rosso team. which used to outsource their car design to red bull (senior team).
Red Bull are just as much a true constructor as mclaren are.
as you said ferrari are the only current team to build their own engines. but they are a minority there.
Renault, Mercedes, Ford (cosworth), do not have a team, they soley supply. there are no 'works' teams like there are in motogp anymore.