About Roundabout: who has priority?: which statement is WRONG?
On a turbo roundabout the ring lanes are separated by a raised lane divider with a solid line on each side; you may not cross it.
The direction of travel is not a choice: on a roundabout you always drive rechtsom (anticlockwise, keeping the centre island on your left).
On a roundabout the rechts-regel always applies: whoever comes from the right has priority.
The arrow on your approach lane is mandatory.
Explanation
trap: base rule applied without checking the signs. Book p.82 - with sign B6 and shark's-teeth it is the other way round: traffic ON the roundabout (which may be coming from your left) has priority, not entering traffic from the right. The rechts-regel only applies here in the rare unsigned situation (p.84)