can I apply for tourist visa with a one way ticket? And then do all the paper work in Shanghai?

Ben, if you want to work in Shanghai, I’m afraid you should get a work Z type instead of the tourist L type. So you are saying that you plan to enter with the L type and then change the L type into a Z type? It’s hard to say whether you can do this successfully.

Anyway, if you are applying for tourist L type, you should provide round way tickets. Alternatively, you can ask your company to write you an invitation letter, so that the tickets are not needed for the application.