B.Sc

Admission is through counseling based on the rank obtained in Indian Maritime University Common Entrance Test (IMU-CET). Please check for your eligibility to pursue this course form the criteria mentioned at the the link provided below:
https://www.shiksha.com/science/course/b-sc-in-nautical-science-indian-maritime-university-t-s-chanakya-navi-mumbai-276979

Hello dear,
This depends upon you in which field you are interested in. Both the fields have same scope in information security. You may go for cyber security, ethical hacking, cloud computing and much more options for future. In B.Sc. It you may go for web development, web designing and more.

No, I don't think you can or the use of doing it that way. When you are doing a degree course, you technically have to spend a lot of time for it's studies. In Hotel Management, it is of prime importance to be there in the class and attend your practical. Soon after you finish your Diploma, you would have to do industrial training for about 4 months. And, if both your IT and your degree classes clashes, then you are going to loose both. But, if you really want to study something extra, then I would suggest you apply for some online certificate courses. For now concentrate on your degree.

Admissions are based on merit of class 12th across schools in India.

Yes, Hansraj has got the best faculty for botany in Delhi University. I myself is a student of Hansraj College and believe me, Hansraj is the best for botany.

If "Not Good" in class 12th means, your less interest in PCM/Non-Medical, then I shall suggest against doing B.Sc. In case you want to improve your grades and have been good at Non-Medical, then you may pursue B.Sc.