MCA

Hello Apurv,
You may refer the link below for the list of top colleges for MCA in Dehradun :
https://www.shiksha.com/it-software/colleges/mca-colleges-dehradun

Hello Kousik,
You are already a student of IGNOU. Then you must be having a brochure of IGNOU. In this brochure eligibility of each and every course offered by IGNOU is mentioned. I suggest pleas have a look at this.

No, you can't do it after completing B.Sc. You can get admission in MCA in NITs. For Masters, you must have a graduation degree.

For 3-years full time MCA course in Pune, you need Bachelors degree in any stream from recognized university and mathematics as a subject in 12th class/SSC. For lateral entry in MCA, you need either BCA or B.Sc (IT/CS) degree. Also, you have to clear the entrance exam like MAH-MCA CET.

MCA and B.Tech CSE are preferable educational qualifications for developer and tester roles in IT companies. Majority of MCA graduates work in IT industry or IT department of business enterprises. There are ample opportunities for bright software professionals to work abroad. Nowadays, long term onsite assignments are scarce but there are good opportunities for short term onsite assignments.

Yes, you can do.
I would love to share the criteria for CEH certification.
PHP
Programming dialects
C+ or C#
Java
Linux
Database
PC Network
But make sure, do the course from the right institute. http://www.koenig-solutions.com/