B.Com

You have a good IELTS score if you want cheaper education cost than MS is cheaper than MBA. Go for any of the above and start working part time. In Australia, you will easily get a part time job which will take care of your living expense, housing rent and transport so that the overall cost will reduce substantially.
I hope it helps.

You can go for Masters as it is easier compared to India in certain aspects.

It depends on the functioning of your university.

Yes, you have a good IELTS score chances are of getting good universities like Swinburne University, Melbourne, La Trobe University, Edith Cowan University to name a few. Just mail the university regarding the correspondence course and ask for help they will surely help you.
All the best.

You should write CWA foundation first.

Hello Md Alam,
There are no minimum percentage required to appear for the IBPS bank exam.
The IBPS is a recruitment agency which conducts IBPS SO IBPS PO, IBPS clerk and IBPS RRB Exam to recruit candidates for the different posts in public sector banks.
The minimum qualification required for the IBPS Exam is graduation degree from recognized university.
There are some other eligibility criteria regarding nationality, age limit and educational that candidates must fulfill to be eligible to appear in the exam.

Mathematics will come to use in the entrance exam itself and post that if you choose to enter into finance field it will be of use somewhere or the other.
Avoid complete negligence of mathematics, at least try to have a basic knowledge of the important concepts which would come to use in future.

An MBA is a good option for you as you are a commerce graduate you can relate to subjects easily. Don't worry if you have not applied for CAT there are other exams which you can target like CMAT, MH- CET, NMAT, ATMA and MAT. Scoring in these entrance exams will help you get admission in a good MBA college.