What is the limit I am allowed to salary sacrifice to superannuation? And can I salary sacrifice if I am on wages or do I have to be on salary?

It can depend on what type of employment, self employed, a employee.

IS it s company sponsored plan with matching funds, is it a tax deffered plan like a IRA or a 401K.

Each has its own tax rules as to how much you can put in and be allowed a tax deduction.

A lot more info will be needed