A: Approximately every 5-10 years. The most recent major revision incorporated better material testing and clarifications on installation dimensions. Always buy the latest version.
A: Partially. ISO 6194 covers rotary shaft lip seals, but DIN 3760 is more specific to cased seals and includes some dimensional differences. DIN 3760 is often considered stricter regarding casing design. You cannot directly substitute one for the other without verifying dimensions. din 3760 pdf
When reading a part number or a DIN 3760 PDF datasheet, look for this marking pattern on the seal itself (as required by the standard): A: Approximately every 5-10 years
DIN 3760 - A - 40 x 62 x 8 - NBR