Exam

In Mains, you should score at least 50 marks to clear and 180+ in advance to get into IIT.
Best of luck.

You should get 60 to 80% marks in JEE.

No, I don't think so. Your marks are good, but I don't think that's enough for getting a government college.
Give other entrance exams also.
Good luck.

You will get 3 chances to appear for JEE Mains. You can take coaching from a good institute to prepare for the same.

It is relatively easy for engineering students because of good mathematics. As CAT tests your verbal and analytical reasoning ability, so, your engineering background will be helpful for you. You may download the syllabus and previous year question papers from any IIM website to get some ideas about

Hi,
No, IIMs consider only CAT score which is a yearly exam conducted in Nov/Dec. This year onwards IIMs have profile based calls. Minimum score required is 93-94 percentile unless your profile is exceptionally good. IIM Ahmedabad, Bangalore, Calcutta and Lucknow are the top 4 IIMs.
Other top college

JEE refers to Joint Entrance Examination. IITs, NITs, DTU, IIITs and other reputed colleges/universities gives admission on the basis of JEE score/rank. It’s a national level engineering entrance exam.

Check out the best universities in state and apply for them.

You have to score above 60 percentile in CAT.

It's only for Vellore University.