NIOS 12th

Yes, you can pursue this course.
Eligibility for applying to the college is as below.
Candidate must have passed 10+2 from a recognized board.

If you had passed board exam, and want to upgrade your education then you can apply for 4 subjects or a single subject. But, if you fail in board exams and applying for single subject admission will be rejected.

Yes, NIOS degree is accepted in every college.

Yes, students of NIOS are accepted in Anna University.

Hi Debmalya Das,
Yes. You can apply for the course.
Please check the Eligibility as below:
1. Minimum Eligibility to Apply-Qualification: 12th with 40% minimum
2. Additional Details
Mandatory Subject : English
3. Other eligibility criteria
Candidate those have BPP with PSS with 50% marks in aggregate from NSOU are eligible.
OR
Candidate must have passed 10+2 in Vocational Courses with 40% marks in English from a recognized board /Institute.

Yes, you can join NDA after completing your schooling form NIOS and from a recognised board with science stream.
Good luck.

You can apply for all the type of government exams available after 12th. So don't worry. You can apply for clerical jobs, defence jobs, etc.

Yes, you can. For joining Indian Army, you have many ways. After class 12th, you can apply for NDA TES entries. After graduation, you can apply for CDSE, NCC, UES, TGC, ACC, SCO, PCSl. In all above case, you have to clear SSB interview to get selected. Also, eligibility for all entries is different. Check it with official website. And for knowing about SSB interview refer www. ssbcrack. com.

In both the boards, you can apply, but not at a same time, as there will be no benefit of doing from two at a time. Because, at every place you can use one at a time. So, no point of doing both a same time.