Any Canadians experienced with Australian working holiday visa? I have some obscure questions that I just cant find answers to.

For one, do I need my passport valid for 6 months to enter Australia?

If my visa expires while in Auz (It will expire on Dec 31st and I plan to be there then) can I get a holiday/visitors visa while still in Auz?

Are the 88 working days ABSOLUTELY necessary for the visa extension?

thanks guys and gals. Really appreciate the help.