Both Universities are equally good. IIT Bhubaneswar is a new IIT and still in the developing phase. But the IIT is a brand name that has global recognition. Being a new IIT the Civil department of IIT Bhubaneswar is not at the same level as old NITs but on the other hand, transportation is a safe career option over construction technology in terms of job security. And despite being a new IIT, this institute has a good placement record. In 2019, there was 68% placement from M.tech courses with decent CTC. The average salary was around 11.4 LPA.
NIT Warangal is one of the best NIT in India. Although the faculties of this university are not permanent, they change frequently and are under the supervision of the Structures division. In terms of placement, this place is also quite good the average salary went up to almost 7 lakhs/annum last year. Regarding education and placement NIT Walangel is preferable over IIT Bhubaneswar as it is the older institute with a large alumni base.
As far as the second question is concerned, M.Tech requires a lot of determination, time, focus, and dedication. If you are not interested then it is a waste of time. You will have very little time left with classes and lab practices in M.Tech 1st year so preparing for other exams will not be that easy. But it’s not impossible if you manage the time properly so that balance is maintained between the preparation of other courses and M.Tech.