Engineering Entrance Exam

I think you won't get NIT, Warangal. Since, your rank is around 12500. You can get chemical engineering in Warangal. In my opinion, you should get admission in Warangal. It is very old and reputed NIT in India.
All the best.

You can get NIT-K, Jamshedpur, Hamirpur, Goa and Jalandhar for ECE, EE, civil and chemical branches.

You may evaluate private universities for doing BTech Aeronautical Engineering. Universities such as Manipal University, Amity university, Anna University are also good options for BTech Aeronautical Engineering. You may refer to following link for list of top Aeronautical Engineering colleges in In

Try calculating your All India Rank (AIR), if you already have one, use a college predictor and search colleges state wise.

If you want to apply for JEE Advanced or want to take admission in NITs, IIITs or IITs then yes, it is necessary to give improvement exam in all the subjects.

JEE Mains doesn’t guarantee any scholarship. It is solely for getting selected for BE/B.Tech institutes.

You can surely get into NITs of the north-eastern regions and certain state/central government funded institutes. You have to wait until the declaration of the AIR and the counselling results.

Yes, you can appear for Mains and Advanced after 2 years of your 12th standard.

Devoting one full year for competitive exam preparation has its own merits and demerits. Dropping a year means that you will get sufficient amount of time to prepare for competitive exams. It will allow you take mock up test and help to score good ranking in competitive exams. However, one year is a

The rank is not sufficient to get CSE, however there are slim chances for ECE/EEE in 3-5th round in lower ranking NITs.