B.Com

If you want to pursue CA with B.Com, then I would advise to pursue B.Com through correspondence. You may find difficulty, while taking coaching for CA and B.Com on regular basis.
All the best.

Sometimes, students may find difficulty while opting B.Com after completing class 12th from science stream and not be able to score good marks because of subject like accounts, law and taxation are different.
All the best.

MBA IB will be logical extension of your graduation studies. You are advised to aim for MBA at IIFT and DSE, DU.

There are many options apart from MBA. The courses like CA or CS will pay even more than MBA sometimes. But, these are not easy and quick. To early learn and earn, you can take small courses on stock markets and make great money, if you can make smart decisions and investments.
People in India are still wary about investing in mutual funds, share market, equity debentures, etc., but with proper guidance and knowledge, they can make you real rich.

NASA majority jobs are for science and technology professionals. You can join NASA in finance function after PG in commerce or management with professional certifications such as CFA. Such jobs in NASA are limited and rare.

Both courses are designed for entry level jobs after graduation degree but BBA will provide you better industry exposure because of discussions of case studies.

It depends on your interest. You can either go for IAS/ IES exams like UPSC/ SSC. You can also go for MBA entrance, but MBA is getting common among students and it is on saturation now. You can also try for LLB. Generally, students after completing CA/ CS go for jobs. If you have interest in law, then it is a good option.