Diploma

Yes, you can do. The eligibility criteria of B.Sc. IT from SMU-DE is 10+2 or equivalent or three year Diploma. Hence you can do from here.

You can opt for JD institute if you wish to do a Diploma in makeup artistry.

Up to my knowledge, you can not do D.Ed because D.Ed is done after a degree course, not a Diploma course.

While selecting the best institute, you need to check some of the important parameters such as recognition, year of establishment, batch size, syllabus, faculty, fees, placements etc. For your reference, here's a list of some renowned fashion design institutes in India:
National Institute of Fashion Technology
National Institute of Design
Lovely Professional University
National Institute Of Interior and Fashion Technology
Institute of Apparel Management
International School of Design
Indian Institute of Fashion Technology
LISAA School of Design

The technical line then opting electrical engineering would be a good idea. But if you are creative and passionate about photography, then you can opt for B.A. In photography. But I would personally suggest you to go for electrical engineering as you can always switch to photography afterward if nothing works out. However, doing vice-a-versa would be difficult.

If you wish to pursue the same course in Masters then you should probably do Masters in the advertisement from MICA, Ahmedabad. This will not only give you an edge over others, but will also help you get placed in a renowned company on a good package.

Hi,
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NIT/IIT after completion of your Diploma course because NIT/IITs does not offer lateral entry admissions to B.Tech course. Only candidates who had completed 12th standard from a recognised board and those who had secured good rank in JEE Mains and Advanced examinations are eligible to get admission in NIT/IITs. Since, you had not pursued 12th standard, being a Diploma holder, you cannot get admission in B.Tech course in NIT/IITs.

No, it's not possible. You've done a Diploma, do you've to pursue engineering after Diploma to gain full degree. You can only enter 2nd year of B.Tech CSE/IT.

Either go for M.Sc or MBA as per your choice.