I hold ZN passport, Do I need visa to China if I stay there three or less days?

Yes, you need to apply one before you go to PRC.

I hold a nz passport and am visiting China for a day trip from my cruise boat on the 13/3/2015 at Xiamen China and docking at Shanghai for my flight home on the 15/3/2015 do I need a visa for the 2 one day visits? I understand we don't require a visa for Hong Kong for our 2 day visit is that correct

Marg

You are suggested to have a double entry Tourist L for your journey.