How long will the immigration allow me to stay in shanghai if i am holding a business visa?

The validity of business visa is 6 months, right? I would like to ask long will the immigration allow me to stay in shanghai if i am holding a business visa?

And I have another question we found an employer in shanghai tru an agency here in the Philippines, after submission of all the requirements they need like authenticated documents etc. and waited for months for the processing of working visa, they told us that it is very hard to get a working visa for health reasons etc. so now the employer said they will apply business visa for the meantime then we go to shanghai to apply for the working visa then while waiting for the release of visa we stay in their company then once it was approved we go back to the philippines and have the papers process. Is this possible? and how long will it take for our working visa to be process? we want everything to be legal before we leave the philippines.. Your feedback will be highly appreciated thank you.