CBSE 12th

Your 10th marks are good. Your 12th marks are on the lower side. Your UG CGPA is also average. Any non-
managerial work-ex, specifically IT is not relevant work-ex for MBA. You will get some points for your work-ex however. Anyways, if you are a General Engineer, you will need to target 99.9+ percentile in CAT. Also, don't restrict your options to just IIMs. There are some amazing non-IIM Schools also in India that you could apply to - FMS, MDI, IMTG, SP Jain, XLRI, XIMB, JBIMS, NITIE, IIFT NMIMS, SIBM, etc.

You can go and study abroad but your marksheet will show that you have reappeared for the exam so it may affect your admission in foreign universities.

Yes, it's compulsory to get at least 65% in 12th.

You can do so but you won't get a college. You can't even get admission in a private college too.

There is many colleges in Bhopal you can get. Some of them are SIST, OIST and LNCT2. If you want to know that which college that you can get on the basis of your rank, then click on the link given below and watch the video till the end:
https://youtu.be/3YAzEP1vgvQ
https://youtu.be/hOlit6Un7l0

Entrance Test
Engineering Agricultural and Medical Common Entrance Test, commonly called as EAMCET, is an entrance exam required for admission to some engineering and medical colleges in the states of Andhra Pradesh and Telangana, India. Many other colleges offering graduation courses like BDS B.Pharma B.Sc. Pharma. D, B.E. / B.Tech etc. Require qualification in this exam.

If you are from general category, then it is very low chance to get admit in this course, because the cut off of this course closed in above 90%. But, you had a little chance in out of campuses colleges.
If you belong to OBC category, then you must get admission for this course. Mostly in last 3-4 cut off, you will get admit for this course.
For more information regarding admission process, visit DU website.

As compared to CBSE, NIOS is bit harder to learn. The NIOS text books has difficult words and Unknown new words. The answers are too long.

The common entry to Bachelor of Arts + Bachelor of Laws [BA LLB] goes through entrance exam. The entrance tests for this purpose are CLAT, ISAT, and AILET. After entrance, some institutes also conduct personal interviews for final selection. There are a few institutes like C. Bhimasen Rao National College of Law, Karnataka which offer direct admission in this course on the basis of merit list.

Prepare for medical entrance for next time, as this would be the only best case scenario for you. Or else, take admission through management quota for the course you wish to get in.