NDA

Hello Rohan,
It's good to see you again hope you are well.
There are lots of aspects and conditions for getting selected in NDA as it is a matter of nation.
Please check it here in the link below for information:
http://www.ssbcrack.com/2016/01/complete-medical-and-physical-standards-for-nda-2016.html

Hello Govind,
Here are few coaching institutes for NDA:
1. Kartar Coaching Centre
Makhania Kuan, Opp. PMCH
2. Vidya Kendra
The ScreeneX, Opposite Krishna Apartment, Boring Road
3. Vikash Coaching Centre
Radhika Complex, 1st Floor, Opp Alankar Place, Nearr Harihar Chamber, Boring Roadd Chauraha, Boring Road

The purpose of Sainik Schools is to help students achieve high level of physical, mental and intellectual achievements required for induction into the officer cadre of the defence services. Government of India has subsidize your education and provided you best educational environment. It will be unfair to common tax payers of India who paid for your education if you do not appear in NDA exam conducted by UPSC with full preparation and motivation.
I leave it your moral ethics to take a decision on whether you want to appear in NDA with preparations or put your soul in cracking JEE.

First, understand that NDA is institute of armed force. For NDA, you pursue B.Tech, but in NDA, government mostly focus on physical training and discipline. NDA is the world most discipline college in his category.

You should write NDA/NA examination which will be held twice a year (April & September). To qualify in NDA examination, you should work hard in English Grammar (I would suggest you to read 'NDA Pathfinder') and in maths. Also, you should be well aware of the general knowledge related to our own country and should fix your timespan of answering a question.
Following these will be enough to crack this exam.

You need intermediate hall ticket number, Adhar number, phone number, mail-ID and passport size photograph. The exam will be conducted twice a year i.e. September and April.

Yes, NDA is very good after 12th but you have to clear all tests in it including written (PCM), physical and you must be physically fit and your vision should be 6/6.

You are eligible to join Indian Air Force as an Airman based on your educational qualifications. You may look at IAF website and apply online for selection. You will be called for written test, physical and medical test. You may look at IAF website for more details.