Science

It is not mandatory that you must have a BCA degree, you can do MCA without BCA.

Stats from both Ramjas and KMC is good. I can say the same for Economics hons for Ramjas. Khalsa had a reputation for violence a few years which has improved and considering the opinions of my peers from Khalsa, it is a satisfactory college. Also, as per my knowledge, English and Economics faculty i

Your question is incomplete as you Haven't mentioned which course you want in MS Ramaiah.
So, with KCET 2544, you can get a seat but CSE, ECE are difficult.
College is around 50-70k (You will get scholarship if you belong to special background) and hostel normal cost around 1 lakh.

If you are looking for career in business domain of IT industry and aspiring for roles like Analyst and Consultant than BBA is better options. If you are looking for roles like Tester, Developer, and Team Lead than B.Sc. Is better. B.Sc. Will give you a technical view and over the years as you gain

No, its not compulsory but it is better if you add chemistry in the best 3.

Jey Keshav, Apart from curriculum, DU is known for high cutoffs, Fest and for College societies. Delhi University has very few colleges which offers (Hons. ). Biochemistry. The colleges are :-
1. Sri Venkateswara College
2. Daulat Ram College
3. Shivaji College
4. Institute of Home economics
5. Deshbandh