Well, it isn't new, but the seller claims to have bought the bike new, and that it has only 930 real km on the clock. In principle the price is not soo bad, as brand new ones go for around 6-6.5k EUR, but if you take it RTW it'll end up with plenty of scratches anyways, so why waste more money than neccessary. In contrast, all the other bikes are ex-service bikes that suffered more or less abuse through conscripts and alike.
HU = Hauptuntersuchung, colloquially known as TÜV, which is the German equivalent of the british MOT, ie. a road safety/road worthiness test. Required every two years and more stringent than many other countries, BUT it only concerns safety (e.g. brakes etc) and various other crap such as lights and indicators conforming to endless §§§. It has nothing to do with reliability, and little with good mechanical condition, although of course a bike in horrid condition won't pass.
AU = Abgasuntersuchung, ie whether the bike conforms to emission restrictions etc, also required every two years. Usually never an issue with OEM exhausts.