MIGRATION TO AUSTRALIA?

I am 36 years old and working for a Public Sector Bank in India in Clerical level and earning around 30000/- per month. I have two daughters aged 15 (in year 11) and 13 (in year 9) at India. My husband is working as Manager in a Super market and has monthly income of $2400. All of have got PR visa which expires during Jan 2011. My children want to study here and then go to Aust for PG courses. We had been at Melbourne for 35 days and we love the country. Since PR visa is due for expiry during Jan 2011, what should I do? Can we manage with $2400 and educate the children? Is it worth taking the decision of migration by leaving the bank job here? If we decide to go after few years will we be given PR visas to join the family?. What are the job opputunities there for my elder daughter who wants to become an engg and younger daughter who wants to become CFA / Bio medical engineer ?Pls advise