B.Com

You are eligible to appear for CAT based on your graduation degree qualification and it will be a good career option for you. However, a full time MBA regular course may impact your articleship and impact your dream to become a CA.

Dear Harry,
You need a minimum of 65% or equivalent in your class 12th and an IELTS score of 6.5 overall with no band less than 6 for the majority of the universities. However, there are a few which will accept overall 6 with no band less than 5.5.
All the best.

MBA in finance is a one of the good options you can think on. As it mostly covers the topics you had already covered in your school and graduation.

Both are well accepted in industry, but for you SAP FICO is a better choice.

After B.Com, you are not allowed to pursue any courses related to science, unless you've studied science stream at PU or at class 12th.

There are many courses available in the market, which you can choose. But, the main point is your interest and capability. So, I would suggest you to go to any specific institute and talk to the counsellor about the courses available there. Through this, you will get an idea about the same, and then you can choose accordingly.

After completing B.Com, there is no science course available.