Colleges in Kalyani

I think, you'll get IT most probably and not CSE.

List of Government college which offer Lateral B.Tech through JELET:
Academy of Technology, Kolkata
Aryabhatta Institute of Engineering & Management, Durgapur
Bengal college of Engineering and Technology
Camellia School of Engineering and Technology
Institute of Science and Technology, Medinipur
MCKV Institute of Engineering, Howarth
Swami Vivekananda Institute of Science and Technology, Sonarpu
Source: http://entrance-exam.net/forum/diploma/list-government-engineering-colleges-offer-lateral-b-tech-through-jelet-india-1821805.html#ixzz5R2nvpsVU

Yes, there is ann ST quota for JELET candidates.

ST seats are very less in government colleges.
Only one in each engineering colleges.
Depends upon your trade rank and how many ST Candidates appeared for your Department.

Yes, you can get Kalyani Engineering College at this rank. There is 70% possibility you can get it.
All the best.

Hi Jyoti, Please refer to the link provided below for the detailed comparison:
https://www.shiksha.com/resources/college-comparison
You should be able to compare various features of the two institutes to help you reach a decision.

Go through the course/college reviews below for details:
https://www.shiksha.com/college/jis-college-of-engineering-kalyani-Kolkata-38245/reviews?course=282002&sort_by=year of graduation&type=question (Copy paste the entire link on the browser). .

Only criteria to get admission in Kalyani Government Engineering College is to get a rank below 4000 in WBJEE and keep an average of 60% in class 12th.
Again, if you have done 5 years Diploma and then want to join this course, you can do so through JELET rankings.
Same for Jalpaiguri Government Engineering College.