Hello, Good day sir/madam, I am Steven Oyins, I want to ask two different questions.

Firstly, the non-criminal certificate needed from the embassy for Z, M and L visas, is it the same certificate applicant acquire from Police Headquarter?
Secondly, I'm presently at China with a S visa, I got a job offer from one the foreign language school.The school want to apply Z visa for me. I want to know whether it's possible for me to apply the visa in Nigeria Embassy in China with the required documents or I am to apply from Chinese Embassy in Nigeria?