Application for tutors

Hi,

I am a Hungarian citizen currently working in the UK. I am planning to move to PRC as an English teacher, through a PRC based UK agency. If the Chinese employer gives the OK, and write me an invitation letter, can I apply for a longer visa, not just the normal 90 days version? I am not planning to go back to Hungary before the travel, can I issue all the necessary documents and process the application without being present, so staying in the UK?

Regards,

Peter