B.Tech Computer Science and Engineering

SNU is no matter the best choice there. It's far better than SRM, NCR with respect to infrastructure, faculty, fee structure, mess and hostel facilities.

Please follow the link below to know about in which college you can take admission in Madhya Pradesh:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor

First of all, the courses you are asking about are totally different from each other. If you want to pursue B.Tech in CSE then Jain University is best as it has various specialization degrees.

Yes, there are some chances that you might get into PEC. There is no surety for it because 53 marks can't confirm your admission to PEC as it is quite a reputed institute, but you hold some chances so go and give it a try.

You should go for JIIT, Noida because it has excellent opportunities as well as good placements stats from the past.

B.Tech lateral entry admission is open for students who have completed 3 years engineering diploma from a Polytechnic or B.Sc from a university. You can choose any path based on your personal conditions and preferences.

Whatever engineering course you choose, in the first semester you will be studying physics, chemistry and mathematics as they are very basic for any engineering graduate. From the second semester, you will be studying your domain means if you have opted for CSE then from second semester you will be studying it.