JEE Main

Yes, you will get the final rank online. The ranks will be based on the two examination of JEE. The rank will be based upon the best score and everyone will get a rank irrespective of the number of times he has appeared. i.e. January and April.

Yes, you will get a seat here with a scholarship. You can easily get the merit cum means scholarship. By the way with such a percentile admission is sure, apply in JOSA portal.

The final AIR will be declared after April 2019 considering the best score out of the two JEE Main attempts for all the applicants, hence based on current percentile we cannot predict for which NIT you will qualify. Wait for the final AIR declaration
Details:
https://www.shiksha.com/b-tech/articles/how-to-calculate-jee-main-rank-from-percentile-blogId-19953.

If you get less than 75% in class 12th, you are not eligible for IIT. But, you can get NIT with that percentile.

It is a little bit difficult to get your seat in the desired college with this percentile. So, just give a try in the counselling.

It is a little bit difficult to get a seat in your desired college because of heavy competition. All the best for your future!

Being an OBC student aiming for NIT Patna. I can say, you hold a chance of getting a seat into it.
Good luck
All the best

Please mention a university/college you are aiming for because every college has a different JEE cut-off.

Admission is possible only through JEE Mains.

MNNIT is a top level NIT. With 82 percentile, you have a slim chances of getting into it. Though I would rather suggest to work hard and put extra effort for the next JEE in April. To be added, you can try for some other NITs and if you have a state quota you may get preferred in those.