Engineering Scope

There is not much, but if you pursue from a good institution German companies will surely recruit you.

BE offers more salary and has better job opportunity than BHM. After BHM, starting salary is less as compared to BE and also after MHM, you will get salary which will be equivalent to BE plus 2 years of experience. Growth in terms of salary and career is good in case of BE and a bit slower in hotel industry.

Yes. Infrastructure is an emerging line.
You may easily get a job as field officer or site inspector.
If you are unable to get a job than contact your local contractor for job.

Mechatronics is a good field. Your objective is also very good. But what you said here is not enough to get a job in NASA. You have to do something extraordinary, something big like Ph.D to get the attention of NASA, and after that only they will call you.
I suggest that NASA is very good but nowadays, ISRO is making good progress in aerospace research, so as an Indian, you should try for ISRO first.

Kindly specify the level of education you wish to pursue. Every level has a different approach.

Hi Ramya, please specify the country and program of your choice.

You are eligible to do Bachelors in management studies (BMS) even after engineering as eligibility to do BMS is +2 from recognized board subject to meeting age criteria. But it may not be a good decision. It will be better if you do MBA or MMS after engineering degree.