What does a speed hump sign look like?

The above is a speed hump sign.

What are the dimensions of a speed hump?

Please see the diagram for dimensions:

What does a 'traffic calmed neighbourhood sign' look like?

TCN sign.

How does a yellow centre line help to calm traffic?

Yellow centre line  divide the road into two equal lanes which reduces the width. Drivers tend to drive slower as they are not comfortable carrying higher speeds in this situation.

What is a 'yellow tail' and how can it help in traffic calming?

It is a part of a 'yellow centre line' utilized to provide positive guidance to motorists on approach to an intersection so they can reduce speed.

What is a 'white stop line' and why is it important in traffic calming?

In urban areas on local streets this is a 30 cm wide line perpendicular to the road advising motorists where to stop at a Stop sign or traffic signal.