M.Tech

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.

Yes, It is indeed possible. It is offered by BITS-Pilani. Since, BCA is a 3-year degree programme, the duration of M.Tech course is 4 years (for B.Tech/BE students, it is 2 years). BITS-Pilani has a separate division called WILP (Work integrated learning programmes), wherein working professionals can continue their higher studies. Wipro offers its candidates M.Tech through WILP BITS-Pilani. Students work on live projects from Monday to Friday, attend M.Tech classes on Saturday and have their semester exams also conducted on Saturday/Sunday.

Yes, you may get. You have a fair chances of getting a seat in IIT just wait for counseling procedure that is CCMT but I have doubt that whether this IIT offer this course in which you want to take the admission since many other IIT too offered this course but this IIT does't because last year also this IIT did not release the cutoff for power electronic. So I suggest you take just verify whether the course is available in the IIT or not. Also check other IIT like Delhi, Bombay this might offer seat in power electronic.

https://cbsenet.nic.in/CMS/Public/View.aspx?page=80
Yes, but be sure that your percentage is at least of 55% in your Master's degree. Please check on above link you will get the details. It is official site also.

You will not get any decent college. I would suggest you to drop a year if you can & again prepare for GATE.
All the best.

Well, it depends on the branch you have your majors in. If you are from a chemical background, surely you will. If not, some skills are required and some basic knowledge as well. After that, you can start interviewing with such chemical industries. Some internships may help you for this.