Hardware & Networking

Opt BE CS or BE IT (If you can). Otherwise, go for BCA & cyber security certifications.

As far as the best Institutes for networking are concerned, you can think of these institutes below. Of course you, will have to check for the locations as well.I-Media Solutions - Pune
Network Systems - Kerala & Tamil Nadu
Networkers Guru - Delhi
EIIT - Noida
Network ACE - Indore
Networks Era - Kanpur
NetworkBulls - Delhi
Networkers Home - Bangalore
Netexperts - Noida.

Computer Science is the best for the Ethical Hacker.

For the networking, if you want go abroad, it is up to you, but in India, for networking the best place is Defence Institute of Advance Technology. It is the better option to opt for.

For cyber security jobs, I think you have to prefer Employment News weekly and visit the nearest police station to work as a member of cyber cell part time.

Yes, you can take admission for the course, as you are eligible. But, you should have the basic knowledge of Computers as per the course. It may be tough for you, if you have not studied basic computer.

There are over 13 Ethical Hacking certification institutes in Kolkata. Please refer to the link provided below for a detailed list of these colleges. You should be able to navigate to the top most colleges/institutions of your choice using the filters on the web page. https://www.shiksha.com/it-software/colleges/ethical-hacking-colleges-kolkata.

You can become an ethical hacker. Just do training from any institute and attend more workshop and seminar on ethical hacking. Practice more and more, and you will become an ethical hacker.