Computer Science and Engineering

You will definitely get a top NIT as your JEE Mains score is good. So do well and work hard.

Yes, you may get an admission in SASTRA.
According to your JEE Mains percentile, there may be 100 % chances of getting a seat in computer science engineering.

Two different branches which depends on your interest. Forgetting about branch, if its a choice between two Institutes I would suggest you to go with VIT as placement wise it really great and even the education is good.

For any queries regarding VIT, Vellore campus, visit this link. https://www.shiksha.com/university/vit-university-vellore-institute-of-technology-29714.

Speaking about VIT Vellore, the CSE branch seats will get over by 2-3k ranks.

You can get placement opportunities in companies like Amazon, Microsoft, Paypal and many more after doing this course.

Yes, any course offered by VIT has yearly updated curriculum. I would suggest you to go for VIT Vellore to pursue CSE as VIT has been ranked number 1 private institution for the 4th time in a row by the Government of India.

Don't worry. Here is the link to find out the suitable college:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor

You can consider following colleges:
Maulana Azad National Institute of Technology, Bhopal, M. P
Motilal Nehru National Institute of Technology, Allahabad, U. P
National institute of Technology, Durgapur, West Bengal
Malaviya National Institute of Technology, Jaipur, Rajasthan
Dr. B R Ambedkar National

These are the top colleges for pursuing CSE.
Indraprastha Institute of Information Technology, Delhi
Jamia Millia Islamia, New Delhi
Indira Gandhi Delhi Technical University for Women, Delhi
Bhagwan Parshuram Institute of Technology, Delhi