What type of visa can stay > 30 days per entry? Or what to do to extend the stay for >30 days?

Generally, China visa is with 30 days each entry, but the embassy issues visa with 90 days each entry as i know. You can write your request for longer duration to the application form that visa officers will take it into consideration according to documents you provide. But if you get a single entry tourist visa with 30 days, it can be extended twice in China, with 30 days each. Anyway, if you get a multiple entry visa, you can leave for HK or Macao and enter China again to active next 30 days.