Government & Defence Entrance Exam

Hi,
NDA conducts entrance exams twice an year. You will have to clear the exam to get admission. Follow this link for more information:
https://www.shiksha.com/college/nda-national-defence-academy-Pune-53488

Yes, you can apply for UPSC for being IAS and IPS. Your degree is equivalent to graduation of course which is the eligibility criteria. The exam has an optional paper which is subjective. There you can chose your graduation subject or some other subject as well as per your interest. It takes more than nine months to prepare start preparing now.

No, Diploma candidates are not eligible for NDA exam. Candidates who have completed the 12th standard from a recognised board or equivalent exam are eligible for NDA exam. Final year of 12th standard candidate are eligible for NDA exam. Your age should be in between to 16.5 years to 19.5 years.

You can choose any course.
According to the eligibility criteria of NDA, unmarried male candidates between 16.5 and 19.5 years who have completed their class 12 or equivalent examination can apply for the exam. NDA eligibility criteria are certain norms in terms of nationality, age limit, educational qualification and physical standards.