IIM

You should prepare for CAT.

Your academic performance is definitely above the minimum cutoff specified by IIMs. Hence you are definitely eligible for admission in IIMs. However you will have to write CAT and do really really well in CAT. With this score you would not get an advantage of being in top 10 percentile based on prior academic performance. Hence you will have to be in top 0.5% of all CAT applicants. If you manage to achieve that, you stand a decent chance to get into IIMs.

Yes, you can most certainly try again for CAT. There is no limit to number of attempts you can take for CAT. However they keep a count of number of attempts. You have decent academic record and a fair chance of getting into IIMs if you do good in CAT. I would suggest you prepare well and give it your best shot this year.

plz check below link and subheader eligibility for details. Evry stream has its own criteria.
https://www.shiksha.com/mba/course/fellow-programme-management-fpm-indian-institute-management-raipur/173493

IITs serves BTech, and IIM severs MBA. Comparisons cannot be made.

I think to join IIMs u need to score good percentage in CAT exams(above 90 percent) and do well in GD & PI. if u can do well in these 3, I think you will be able to join any good colleges and the graduation marks won't matter tht much

Nah! Not to worry about that. You just need 50% on your degree at last.

Minimum 50% is required in bachelors degree for sitting in CAT. Don't know about admissions.