Law / If I change my job in Poland without obtaining a new work permit, will this affect my residence visa [21]

Currently, I'm working in Poland on work permit. I want to change job.
I understand I need to obtain a work permit from the employer I intend to work for.

I would like to know following things:
1) If I leave my current job without getting new work permit, can my current employer make my residence visa invalid?
2) Can I stay in Poland without getting a job until my residence visa expires?