Diploma

You can refer to the below mentioned link:
http://goo.gl/dkzMBo

Yes, you can do CCNA certification course. If I talk about CCNA scope so after completing CCNA, you will get few benefits:
1. Importance for recruiters
2. Unique learning network
3. Knowledge plus experience
4. Good for career
5. Builds a base
6. Good for the employer
7. Proof of certification
To Know more brief above mention point then visit here:
http://www.selfgrowth.com/articles/is-doing-ccna-certification-really-worth-for-networking-professionals-0

As a nutritionist, you can find employment in :
-hospitals
-health and recreation clubs
-canteens
-nursing care facilities
-teach the science of nutrition and dietetics in colleges and universities
-catering departments of star hotels
-research labs of food manufacturers
-in health departments of government.
You can also work as a consultant or do private practice.

Hello Sandeep,
If you have completed your Diploma and want to graduate in IT, I think you should prepare for LEET exam. This exam is will help you to get admission in the second year of B.Tech.
All the best.

Hi Sourabh,
There is a placement cell at SXCKOL. You can register yourself for campusing opportunities.
For further details, please visit: http://www.sxccal.edu/placementcell/placementCell.htm
What I can say that multimedia students do get good jobs and they are working in various companies and even they are doing freelance.
All the best.

Visa has nothing to do with the course, so there is a fair chance of visa approval or rejections (50:50).

Yes, you can change your stream. Some colleges allow Diploma holders to change their stream in B.Tech.