What are the rules regarding professional confidentiality and data protection (Datenschutz) regarding student personal information in a Swiss driving school?

1. Collect every potentially useful record at enrolment and decide on its purpose later
2. Process only the student data needed for a defined purpose, protect it appropriately, limit access and retention, and disclose it only with consent or another valid legal basis
3. Keep all student files indefinitely because deletion would remove evidence of past lessons
4. Send progress information to any family member who asks, because they may be helping pay for lessons