Petroleum Engineering

Depends on which branch you want and your category. If you are from general category then I don't think you will get either of CS,Mechanical or Electrical. It depends on what rank you get in rank lost prepared by Maharashtra government. Generally the cutoff ranks for CS, Electrical and Mechanical at MIT are below 3000.

There are still people working in these area, but the major problem is funding. Even though the funding is huge, but it is concentrated only in a few bunch of colleges. Also, with the advent of new technology, there has been a shift of focus towards renewable resources I guess. But, if you check in universities outside India, there is still a large amount of research, which is happening in this area.

You should apply for government jobs or try for walk0ins going on round the year.

Please check for your eligibility to pursue a B.Tech. in Petroleum Engineering (Lateral Entry) at Rajasthan Technical University from the criteria mentioned at the link provided below. Admission process for this course is also mentioned at the link provided below:https://www.shiksha.com/b-tech/course/b-tech-in-petroleum-engineering-lateral-entry-rajasthan-technical-university-kota-270977

B.Tech lateral entry course is provided by NIMS University, but not necessarily for petroleum engineering, you need to check with the college for the same.
https://www.shiksha.com/b-tech/course/b-tech-lateral-entry-nims-university-nims-jaipur-236275

It depends on the rankings of the people and the availability of seats there.

After petroleum engineering, you can work in production with various oil and gas companies. The average package is 4 LPA.

Computer has more scope as IT industries are in uptrend nowadays.