Do I need visa for, Wellington. austrialia, Hong Kong and Singapore

I am traveling to Wellington to visit friends for 2 wks stay, on the way I will be in Hong Kong for 4 days.
On my Return home to Manchester I will be in Sydney for 20hrs and going out of the airport to see the bridge and opera house then onto Singapore for 4Days.

Will I need entry permit for each country or just some?

Thank you and Regards
Beverley