CA

The combination is as:
1. CA + MBA.
2. CA + CFA.
As package is concerned, first option is much better. It depends on institutes and its ranking. Second option is better, if you want to make your career in education sector. Both options are equally good for those, who want to go abroad or want to work on foreign assignment through Indian companies.

No, a student from any stream can pursue CA.

Quantum of opportunities in order of precedence are as follows: CA, CS, actuarial science. CA is the best option to set up your own practice.

After 12th, you have to appear for CPT. It is conducted twice a year then you have to go for IPCC (two groups). After clearing 1 or 2 group, you can start your training and after that you have to appear for your last and final exams in two groups.

Both CA and CS are good options. It depends on your ability and skills. CA has more prospects and job opportunities as compared to CS. But many companies offer amazing salary to CS. If you are trying to pursue B.Com + CA, you will need to study at least 4 hrs every day. Also, you will need to do an article ship to get the CA / CS certification.