Diploma

Yes, you change the branch in B.E/B.Tech after Diploma. But, it varies from university to university.

Diploma in Cinematography: Eligibility
Students need a pass in class 12th examination in any stream. There is no minimum percentage requirement to seek admissions. In some institutes students above 15 years of age can also apply for admissions.

Visit the below link :
https://www.shiksha.com/hospitality-travel/travel-tourism/colleges/diploma-courses-Mumbai.

There are many graphics and animation courses available and anyone can do that after 11th,12th, of after graduation. My sister had done her 12th and after her 12th she joined a course from Arena Animation company, The course fee was very high but still, we managed and letting her finish the course (

Candidate must be graduate in relevant stream or its equivalent qualification from a recognized university to get eligible for the course.

You can refer https://www.shiksha.com/engineering/colleges/diploma-computer-science-engineering-colleges-Lucknow
Not sure if they conduct entrance exams or not. Usually, most colleges do.

Eligibility Criteria for admission in Diploma in Audio and Music Production - Candidate must have passed 10+2 from a recognised board.

For which Diploma course do you want to know? If you are asking about PGDM, then yes while doing PGDM there are some colleges who provide internship.