Delhi

NIT, Trichy is one of the best institutes for CSE. It is top among the NITs and placements for CSE are pretty good here. The only issue you might have is of adjusting to the new environment. Also, Delhi is much better to live than Trichy. So take your decision considering all the facts.

The selection of subject based on best four means you have to arrange your marks in descending order and whatsoever is last don't include in the best four.

For outside Delhi category, there are only 5 seats in the main campus. So, it would be hard to get main campus in the first round. You will definitely get VIPS or Amity. Do not go for IIMT. Whatever college you choose, always hold the upgradation option because you can make it to the main campus after few counselling rounds, and yes there is the option for migrations also.
All the best!

Yes! You can get a good college according to your rank!
Good luck!

IGNOU is your best option for Distance learning in any UG or PG course. More details abouy the programme can be found below
http://ignou.ac.in/ignou/aboutignou/school/sopva/introduction.

All government colleges take admissions on the basis of the entrance exams result. Since you didn't give one it is highly unlikely now. One thing that you can do and don't place your hope on it. You can wait and later contact the colleges to see if they have any seats vacant or they are conducting spot counselling.

Delhi University, colleges under Calcutta University, etc. are the best for B.A. Political Science Hons.
Other colleges are also there-
Please check this link once.
https://www.shiksha.com/humanities-social-sciences/political-science/colleges/b-a-colleges-india

There are 100s of college which provide BCA course!
Choosing one of them is really a tough decision!
Some of the best colleges are:-
ITS mohan Nagar
IMS Noida
IMS ghaziabad
ASB Noida
Amity Noida etc.
These are some good college which are government recognised, good infrastructure with good faculty team and have all possible amenities like modern labs, huge library etc.
Choose wisely!
Good Luck!

Uhh have to fill the application form.
2. Thn some documents r also attached lyk 10th ,12th marksheet, certificate, anti ragging form etc. And the procedure is vary from college to college. Sooo vist the clg himself nd alsoo direct contact with the clg .