NDA

You should approach a physician and tell him or give him the medical eligibility criteria page from notification. Only he will be able to test you properly.

NDA was established around the idea of treating everyone equal and giving the same training to everyone. This is the main reason girls are opted out here because the candidates are exposed to such challenges that most of the girls wouldn't be able to keep up with boys. Since equal training has to be given to ensure the ability of NDA alumni, girls candidate cannot train with boys.

You can join NDA after qualifying the NDA exam conducted by UPSC. But Raw recruits its employees from different forces in India. That means Army, Police, CISF, etc. They do not release vacancies but instead see a person's potential and directly recruit him.

Yes, it is. Surely, you can understand why. Army personnel have to be at their physical best to survive the tough conditions they have to be aware of their surroundings all the time. Colour blindness may obscure your perception of the environment.

Class 12th passed or appearing and between 16.5 to 19.5 years old male candidates are eligible to enrol.

Study your class 12th science thoroughly. Read English Newspaper every day. Also, learn history through your coursebooks. There is no shortcut to success, remember this always and study hard.

If you are not more than 19.5 years old. Older than that will not be eligible.

NDA Exam is conducted by UPSC twice a year. You should be class 12th pass or appearing and less than 19 years of age. The syllabus of NDA is same as 12th Science and Maths. Also, you would need to make your English and GS strong. After you qualify the written exam, you will be called for SSB interview which is a 5-day interview that tests your personality and aptitude. If you qualify that too, you will give the medical and physical test. After that, you will be admitted to NDA.

Your eye power is quite low to be even qualified for Army Medical Test which is much more relaxable.
-6.5 means that you must habitually wear glasses and that may not be possible in Personal Training.

If and only when they are in same city and their timings don't conflict with each other. NDA exam is usually conducted in morning at around 10.