Diploma

Please check the prospectus of the course provided by the university to get all the details regarding admission procedure, eligibility and syllabus.

Hi
You will have to appear in the entrance exams. The process differ for different colleges. Here is a link enlisting colleges which offer Diploma in aeronautical engineering, click on each to find more:
https://www.shiksha.com/engineering/colleges/aeronautical-engineering-colleges-india?cl[]=13&ss[]=sp_10&uaf[]=course_level&uaf[]=credential&rf=filters&cr[]=10

Hi
The admissions will start in the month of April/May, but you will have to check the website and the prospectus for the complete details.

Yes, you can go for Diploma in forensic science after competing your B.Tech degree, but it would not be of much benefit.

Yes, after you have completed your diploma you can get admission in engineering through lateral entry and directly into 2nd year.

There is no age limit. If it is your passion, then go for it. In fashion design schools you have 19 year olds learning fashion design as well as 45 year olds.

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.

Diploma holder students are not eligible to apply for NITs. You can appear for JEE Main exam to be eligible for JEE Advanced exam. You can take admission in IITs but in 1st year of engineering.