Very similar to the Mercedes.
Yes, and there are indications that the types 601/602 from 1977 onwards are based on it.
I once had a Hanomag employee as a bedmate in hospital who told me that he had worked on the design of the dashboard.
In the mid-70s, you could regularly see only lightly camouflaged pre-production models with test drive plates in the city of Hanover. It stands to reason that the Hanomag test track in Hanover-Linden was used for practical trials.