Maths Spl

You can pursue B.Sc. Maths from IGNOU. Visit IGNOUs official website and find your local study center.

These are do or die chapters in mathematics. Limits, continuity & differentiability. Application of derivatives. Definite integration.
3-D geometry. Sequence & Series. Probability. Straight lines. Circles. Matrices. Complex numbers.

Don't stress out too much. Choose what you are comfortable with. Select a subject that you like and are interested in. If you are asking for opinion then I would suggest choosing social studies because it contains history and that doesn't change with syllabus.

There is no such ranking of a department of a college but this college is one of the top 5 science colleges of DU.
The only disadvantage of this college is that it is an off-campus college.

Financial studies don't require maths in 12th. It is not compulsory. You can pursue BBA, MBA and PGDM without taking maths in 12th.

Yes, you can give ICAR without a doubt. But you have to clear the maths compartment to get your result. You can not be failed or have back log in any subject before at the time of admission in a college. Try to clear it as soon as possible and in 1 attempt because then you may have to wait another year to do so.

You should have at least a bachelors degree to pursue this course. Subjects in 12th don't matter much. You are certainly eligible for this program assuming you have done bachelors.

You can definitely go for BBA and MBA. This provides ample of opportunities to explore once you have a degree. A stream does not matter for BBA and MBA but it will be a little bit difficult.

University Physics by Resnick and Halliday
University Physics by Sears Zemansky
Irodov's Problem in Physics and Solution
Calculus by GP Thomas
Loney's Trigonometry and Coordinate Geometry
Hall and Knight's Elementary Algebra and Higher Algebra
Organic Chemistry by Morrison Boyd.