USA

Hi Satish,
Yes, of course you can study after 12th . A bachelor's degree in a desired area of your interest is the best option. Decide where you want to study and accordingly you must prepare. Do share your profile if you need further guidance.

You can go for summer activities,though they offer undergrad but that is after 12th

The budget would vary from 30-40 L for 2 years.The expected median starting salary for recent MBA graduates in the United States will be $100,000 this year.specialization would depend on your interest.
Top Business Schools in U.S.A. - MBA Rankings
US News Rank Business Week Rank University
1 5 Harvard University (MA)
1 9 Stanford University (CA)
3 1 University of Pennsylvania (Wharton)
4 15 Massachusetts Institute of Technology (Sloan)

Dear Pranav,
There is no minimum requirement. The general standard, you must have first class percentage to get into the top universities.
Regards

Germany is world leader in automobile industry. It is one of the largest export earner because of its R&D and innovation strength. It is suggested that you prefer MS in Automobile engineering in Germany. Not you will get quality education but will also get opportunity to work with leading Automobile manufacturing & R&D companies.

Dear Hardik,
Are you looking for Fall 2016 or Spring 2017? Many university deadlines have already crossed and if your looking to apply for Fall 2016, you should apply Asap. Do let me know

Hi Pramod,
You must first have work experience to be eligible for MBA in UK. Secondly you must take GMAT and IELTS or TOEFL. If you are looking for colleges accepting freshers you may refer to this article
https://ask.shiksha.com/i-want-to-do-mba-but-without-cmat-or-gmat-exam-and-want-to-study-in-us-or-uk-mba-in-marketing-sir-can-it-be-possible-qna-3508177
You should consider doing a MS Management or MS Marketing.

Hello Unni,
Job opportunities mainly revolves around research in organizations such as NASA and teaching positions. In depth knowledge in mathematics, computers, statistics and physics and excellent academic grades are must for job prospects in US. A PhD is also important for an astrophysicist.
Regards

During Spring when candidates are less.