If you have the marriage certificate with your Aussie husband and proof that you are the monther of your children (birth certificate) then you shouldn't have problem to apply the spouse visa. To make sure you can visit the Australian Consulate-General in Wan Chai for the enquiry
Not sure what do you mean by "申請到visa後係埋可馬上做宣誓辨手續,取回我的MPF" What is that for?