Chemistry Spl

Hello,
Its a common conception that math is always tough :P
But, if you are interested in joining medical related courses or biotechnology then you must study biology. But you will be eligible to engineering courses as well.
If you choose C.S. you will be restricted to join engineering. As you say you are well versed in maths, I suggest you can take math+bio as your combination as the career & variety of courses will be wider.

Look, according to your marks you can easily get admission in DU's affiliated colleges, just fill the form and go for it.

Seems like you are qualified.
If you have got CRL rank in JEE Advanced, then you are definitely eligible for counseling.
https://www.resonance.ac.in/reso/news/jee-advanced-branch-allotment.aspx
Check this branch and IIT college predictor.

Chemistry. No type of engineering can match it. It is unique as well as provides broader options with physics, engineering people will always compete with you.

No, you will have to clear your compartment first to get admission for BA.

S P University is better.
The College is pretty good. Teachers are well qualified, helping and friendly. Infrastructure is somewhat good, but it hardly matters sometimes, because the environment developed there is pretty good for studies. The industrial exposure that you get is also good.

Analytical chemistry, as this will help you to get in analytical research area in chemical, pharmaceutical, metallurgy, food processing, leather and other industries.