B.Tech

ELIGIBILITY OF THE MASTER OF ARTS [MA] (POLITICAL SCIENCE)
The basic eligibility for admission to MA Political Science has been mentioned below.
Bachelors degree in any stream preferably Arts and Humanities
Students with a graduate degree in other streams can also apply
Minimum marks required vary form 45% to 50% in graduation and may vary for different universities
The minimum pass percentage is higher for non-humanities courses
So, you are absolutely allowed to join MA after B.Tech.

Salary wise, they are about even. However there is going to be a MUCH greater demand for biomedical engineers and it would be quite easy to form a startup company in that field. Also with greater demand for biomedical engineers, there salary is bound to go up. Just make sure as biomedical engineer you don't get stuck in a research position unless you really like it because their job is very laborious and underpaid. If your passion for both is equal then go with biomedical engineering. If your passion for one is greater then choose that one.

BTECH IS A DEGREE
The Bachelor of Technology (Latin Baccalaureus Technologie, commonly abbreviated as B.Tech.; with Honours as B.Tech. (Hons.); or BTech) is an undergraduate academic degree conferred after completion of a three-year, a four-year, or even a five-year (such as in Nigeria) program of studies at an accredited university or accredited university-level institution. B. Tech is considered as skill-oriented course. The degree is conferred in the Commonwealth of Nations, the United States and elsewhere.

Yes, you are eligible for this college.

Your rank is not so good. So, there are very less chances to get this branch.

No. It only takes admission in AME that is aircraft maintenance engineering which is governed by the DGCA.
It is also a good course and has job scope too. If you are willing to pursue this course then go for it.
Best of luck. For any further query please feel free to ask.

No. It only offers AME which is governed by the DGCA. http://www.iiagroup.co.in/ame-courses/
You can check the link and for the course as well as different information also.