M.Tech

For admission in Ph.D civil, you need to apply to the institute and thereafter you will be called for an admission test.

You can get some help on this link:
https://iitism.ac.in/index.php/placement#phomem.

Cyber Security is itself an important aspect. However, it also depends on your own capability of understanding the entire subject. You can also pursue CISSP, certification which covers all the aspects of cyber security. I hope this would suffice.

Of course, you can pursue M.Tech twice, but both M.Tech have at different duration of time i.e after completion of first, you can do 2nd. Or, you have do 1st as distance learning mode and at the same time you could take admission in 2nd M.Tech degree with your valid GATE score card. Hope, I have given complete details regarding your doubt.

No, M Tech is not recognized through distance education mode by AICTE.

Among all of these colleges, BIT Dhanbad is best for M.Tech. It is ranked among the top of the colleges in India.

The best college in Bangalore for M.Tech is Indian Institute of Science:
http://www.iisc.ac.in/.
You can check the official website for more information.
Hope it helps.