The roads could have some more details like maxspeed, number of lanes for the "Landesstraßen", surface and sidewalks (if they are not separated from the road use the sidewalk-key and not separate footways).
Also some access restrictions could be useful. E.g. most of the small service ways seem to be private, not sure about the tracks, they might be restricted to agricultural vehicles.
And if you are interested in public transport you could add the local bus routes and add some more details to the railway line.