Should I find job before applying WHVP? (Work Holiday Pass under the Work and Holiday Visa Programme).

No.

Note: The Work Holiday Pass does not exempt you from complying with registration requirements to practise in Singapore for professions such as medicine, dentistry, pharmacy, architecture, law, etc.

Any other requirements for WHVP?

For the Work and Holiday Visa Programme (WHVP), in addition to being Australian, as well as a student or graduate, you must be able to support yourself financially while in Singapore.

You’ll need to declare sufficient funds for your arrival, stay and departure.