Robotics

Hi Sabbir Ahmed,
The ideal course is B.Tech or B.E. In Mechanical Engineering. Robotics and Automation are taught as majors in this discipline. You will find colleges abroad offering B.Sc. Courses in Robotics, AI etc. But then its is always better to opt for mechanical engineering for a strong foundation and conceptualization.

I think, it depends upon on your interest but as your core is mechanical. So, mechanical is the best for you because you also have knowledge of mechanical subject as you are studying in your Diploma course.

Depending on the qualifying exam percentage, you will get the scholarship. Based on your prediction, you will have 50% scholarship on your tuition fee.

CSE of IIT Bombay is known as the cream branch of India. Nothing more to say.

Yes, PSG is one of the best colleges for robotics and automation in India. You can take admission in the same.

There are short-term courses in robotics but most of them are online courses, mentioned below are some of them:
By Coursera:
1. Robotics - Capstone
2. Intelligent Machining
3. Robotics - Estimation and learning
By University of Pennsylvania:
Robotics - Locomotion engineering
Robotics - Vision intelligence and machine learning