No
Tsunami warnings in Australia are provided by the Australian Tsunami Warning System. This is a national collaboration between the Australian Bureau of Meteorology, Geoscience Australia and the Attorney-General's Department. More information about the Australian Tsunami Warning System can be found at the related link below.
No, Sydney was not directly affected by the tsunami that hit Brisbane, Australia. Tsunamis are usually localized events and their impact is limited to specific areas along the coastline where they make landfall.
It is not certain.
The deadliest tsunami was the 2004 Indian Ocean tsunami, killing almost 230,000 people.
That would depend on where the tsunami struck and how big it was. Much of Australia's coastline is very sparsely populated, but a tsunami hitting one of the coastal towns or cities would wreak havoc.
No
Theoretically speaking, any coastal settlement in Australia, including Sydney and the Opera House, could be subject to the force of a tsunami. In 2007, a tsunami warning was issued for the eastern coast of Australia following an earthquake in the volcanic region of the Solomon Islands, but by the time it reached Australia, its highest wave was 15 centimetres. For more details of possible tsunami risks to Sydney and Australia, see the link below.
the us, Australia and countries sunrounding it.
230,000 people (2004 Asian Tsunami)
Papua, New Guinea is most susceptible to tsunami hazards.
yes.