I am in china on a z visa. I entered the country on August 22nd.

I have my residency permit which is Valid until June 15th. What if I want to stay for 2 or 3 weeks longer than the June 15th date on my residency permit? What and how do I accomplish that.

Also, with my residency permit can I go to hong kong or say to vietnam and return without any problems? Do I need to apply for any additional permits?