Marine Engineering

The eligibility criteria for this college is 60% Marks in PCM and 50% in English in Xth and XIIth.

Hello Shubham,
I am attaching a link that will give you the required information about admission in IMU.
http://www.imumumbai.com/TScontacts.html

I've always talked about TMI, whenever it comes to academics or placement. The people over there are Magicians, who manage to get companies even when the industry was sinking and companies went Bankrupt.
If you manage to perform well and stay without any E Grades, you'll have an appointment letter with you by the time you pass-out.

After finishing your marine engineering you have got two options as far as I know.
Option 1: Normal way of doing UPSC exams and progressing.
Option 2:
Sail on ships as an engineer officer or deck officer, rising up to the ranks of chief engineer / Master mariner and earn experience for atleast 5 years. Following this whenever there is an opening in DG shipping for Surveyor posts, you can register yourself in UPSC following which, you will be interviewed for the job by UPSC panel. If successful, you will be able to take up the government job.

No, you can't pursue it after diploma from an electronic background, however, you may have the chances for some colleges.

It is possible if you go for private university, but for government or aided, it's way too hard.

You won't get any college through JOSSA. I would recommend you to look for a good private college.