GATE

Komal, there are many good private universities in North India that have a reputation for providing quality education. They offer admissions in PG engineering courses on the basis of GATE scores/ their own tests/ marks in previous qualifying exams, so, try there.
Good luck.

atleast 30% of maximum marks are safe for an sc candidate
please upvote

Auto mobile is a specific brach of mechanical engineering in many institute so the gate do not take specific exam on it now a day. You should appear in GATE exam and the GATE score will be valid to get admission in automobile engineering too.

Yes you are eligible to appear in GATE. you should visit the website of IITs for syllabus,eligibility criteria. if you secure a good rank in it you will get admission in IITs, like IIT roorkee

If you want to do job in the industry than after some years you required a master degree, for managerial post sometimes MBA is the best choice but m.tech is a core field and you spend four year so you can do in the engineering itself unless you got a very precious business school like IIMs, xlri, MDI, FMS and IITs etv

It's bit difficult to do preparation with job. however many people did it with job, what actually required is that your continuous effort. you may join some test series to be active. Bring last ten year question papers and go for your strongest subjects first then cover other one by one.