1) If I leave my current job without getting new work permit, can my current employer make my residence visa invalid?
When can a work permit be revoked?
In the following situations the voivode may annul - revoke an already issued work permit:
- circumstances or evidence on which basis the permit was granted have changed and the voivode was not informed thereof;
2) Can I stay in Poland without getting a job until my residence visa expires?
I think it depends if your residence visa is depended from work permit.
I've heard that before people had to leave Poland instantly when they're fired or quit the job and that the law was changed so now they can stay for 1 month after finishing job in order to search for a job. But I am not sure if this law is already implemented and weather it requires extra permit.