Whats Street legal in Australia

[MPowergermany]

Hi,I´m new here and I´m from Germany,the country in which nearly everything that makes fun on a bike is not allowed.

How is it in Australia?Are you allowed to build everything into your bike you want or do you have also guidelines?

Are slick tires on a street legal car or bike allowed?
Are NOS systems in cars or bikes allowed?
Do you have a noise limit for the exhaust?
Do you have an emission limit or are you allowed to have as much emissions as you want( an emission law often handicaps high horse power)

I hope you can help,

best regards,Marco from Munich,Germany