B.Tech

You must have above 55% in class 12th.
Do not have negative marks in JEE.
If you full-fill 1 and 2 you will get admission and counseling is just for showing off. You can go anytime during admissions and get yourself in.
Except CSE, you should not take any branch! No interns and No placements.
If placements are there. AVG is of 2 to 3 lakhs. Which do not worth a Engineering degree
You can either choose any college around Delhi. because in Doon ( as my personnel experience) after 8pm .You cannot buy a packet of chips.
The college is at extreme point, scenery from there is good. but after 4 years what matters is PLACEMENTS. Which till now is nothing as compared to other top universities in Uttarakhand.

What is the fee structure at Dhemaji Engineering College for a B.Tech in CS branch?
The fee structure of Dhemaji Engineering College keeps on changing every year for the newcoming batches.But,the fee fixed for one batch is the same for the rest of the remaining years.
Talking about 2020, thats when i got into Dhemaji Engineering College,the fee structure was as follows:
Tuition Fees : 1,19,000 p.a
SSEPL : 20,000 p.a (This is Compulsory)
Hostel + Mess Charges : 67,000 p.a
So,this sums up to 2,06,000 per year but in the 4th year,there is no SSEPL fees.This sums up the Net fees to a total of 8,04,000 for the 4 combined years during B.tech including Hostel Mess.
Note that this fee structure was for the admission year 2021. This will be more or less the same for admission year 2022 or 2023 also.But,to be on the safe side,as the college has now become an University in Feb,2023,so there may be some changes in the above mentioned fee structure.For latest fee structure you must contact the college authorities.

There are many Online Course but first, you should be knowing what to learn and mainly need Interest. During when I was doing my Engineering most the website like Coursera Provided Free Course but now it all Paid Certificate by the way its good if you put your money then you have the Interest to Complete it within Time. :P
There are many Course like
Hardware and Systems Technology. Network Systems Technology. Systems Development. Data Management. Introduction to Programming
Computer Engineering. Computer Forensics. Computer Networking. Computer Programming. Cyber Security. Database Administration. Information Security. Information Technology. Software Engineering. Web Development.

First of all, You have not mentioned a course name. However, Placements are good at both colleges. The highest package offered by St. John College of Engineering was INR 10 LPA and the lowest package offered by St. John College of Engineering was INR 3 LPA. The highest salary package offered by Shree L. R. Tiwari College of Engineering was INR 1 crore by Google. Microsoft, Infosys, TCS, LTI, etc. , visit the Shree L. R. Tiwari College of Engineering campus for recruitment. More than 80 percent of the students got internships and almost all students got placed at Shree L. R. Tiwari College of Engineering. For more college comparisons, you may visit the Shiksha college comparison page. (https://www.shiksha.com/compare-st-john-college-of-engineering-and-management-vs-shree-lr-tiwari-college-of-engineering-shree-rahul-education-society-id-332043-279159)
I hope this will help you.

There are eight campuses of SRM University so the cut-off for CSE in all these campuses will not be similar because as per current trend maximum aspirants of SRMJEEE wants to join CSE in kattankulathur campus because CSE is a premium branch and kattankulathur is a premium campus of SRM University because here they will get maximum opportunities for placements compared to other campuses.
Officially SRM University never published the cut-off for specific branch and campus but as per previous year and current trend CSE in kattankulathur campus has been given to top 5k rank holders of SRMJEEE. As you know that phase 1 and 2 already done and maximum number of seats are filled so in phase 3 you must have to get a rank below 2k to secure a seat in CSE at kattankulathur campus.