I only know for certain it’s by law in Norway, and I suppose I just assumed it was for other European countries, too, since a shared bathroom is rarely to be seen.

First time I saw that sign I was baffled, as in most other countries I’ve been to it’s illegal for employees to use the same facilities as guests. Then I got a bit grossed out thinking of the fact that employees apparently need to be reminded to wash their hands.

Gasket thickness typically don’t matter (within reason). An exception being in installs where a thick gasket or, more likely, a spacer is used to keep some engine heat away from the carburetor to prevent things like vapor lock.

I wouldn’t hesitate to use whatever is in the aftermarket kit as long as it fits well.