Do I need to apply for a China visa if I have HK passport, China card & HK ID?

Hi, I am planning to visit Beijing for few days on Sep. and will take direct flight from Vancouver. I was born in HK and now I am a Canada immigrant. I have HK passport, China card & HK ID.

Do I need to apply a visitor visa if this is the case? Cause I called Air China & travel agent, some said I need to, while other said I am ok..

If I need to apply a visa, do I need to apply personally or if I can give it to travel agent to apply for me?