Do I need another Z-visa?

I was given a Z to join my spouse who works in China. I now have a residence permit and am currently job hunting.

1. When potential employers ask if I am authorized to work (during the application process/non-verbal), what do you think my answer should be?
2. I realize I will need an Alien Employment License to be able to work here but will I also need to apply for another Z when I find a job?

I would appreciate your thoughts. Thanks.

-PB