B.Sc

Hi Sujata,
When are you planning to study in US? To get a job in USA is not easy. A three year Bachelor's degree is not accepted by most of the universities. They require 16 year of education. So, you must research well and narrow down your choices. If you are looking for a one year affordable course, you can check options in Australia or New Zealand.

You can pursue M.Sc, Ph.D or MBA. You can also try for UPSC exams.

You can not do B.Sc from ISRO. IIST is an institute established by ISRO for studies in aerospace engineering. Admission is on the basis of JEE conducted by IITs.

Yes, you can do Ph.D and fellowship courses. You can do some research.

You can go for M.Sc nursing or Ph.D in any medical subjects such as, anatomy.

You can consider the below mentioned courses:
1. B.Sc zoology.
2. B.Sc botany.

MBA will help you to improve your skills and develop new skills. You can choose any specialization according to your interest.

Yes, it is good, if you are opting for IIM to pursue MBA. You have to prepare for accounts subject as it is related to the management subject.