MAT

Better than just selecting only one college, I would like to suggest you appear for CAT, MAT and CMAT. This will open the doors of many other good institutes for you.

The AIMA or All India Management Association conducts MAT 4 times every year and there is no limit to individual attempts, so you can appear for MAT four times in a year, However, most of the top B-Schools consider only the Dec or Feb edition of MAT so it is advisable to appear for the same
All the best.

Yes, it is valid but the thing is that in which college, you want to take admission? They will see that your marks is above eligibility criteria or not.

No ,you can apply in the next year.

Hello,
Your score is good for admission purpose as per previous year selection procedure. But for this, there are some changes in the selection process and policies so cannot say whether you'll get admission or not.
But your score is good so everything depends on your GD PI
Good Luck

Top MBA Colleges in India Accepting MAT scores are mentioned at the link provided below:
https://www.shiksha.com/mba/ranking/top-mba-colleges-in-india-accepting-mat/2-2-0-0-306
Top MBA Colleges in India Accepting ATMA scores are mentioned at the link provided below:
https://www.shiksha.com/mba/ranking/top-mba-colleges-in-india-accepting-atma/2-2-0-0-9180

First, shortlist the colleges based on the last year cut-offs. Then, you can directly apply to the college of your liking from the shortlisted colleges. You have to visit the college or fill the form online if applicable.