Re: Do I gave to inform my Gemeinde about changing employers?
Conditions that need to be met to inform the Gemeinde/Kreisburo/whatever:
-being a student and going from an internship to "normal" employment. Your student permit (even a B) allows work up to 40% so if the new contract is more your current permit is not legal. You present the contract to the Gemeinde and you wait for a new permit tied to the contract instead of the university.
-being on an L permit tied to the ending contract. If it was a fixed-term contract you will need to renew your permit with a new contract. If your permit was expiring I guess you would just receive an invitation anyway.
These are from personal experience.
If you're on a B permit that was issued for your previous contract, from what I understand you don't have to do anything additional and you can just take the new contract to the Gemeinde when they invite you for the next renewal.
Nothing is fool-proof to a sufficiently talented fool