BCA

Yes, you are eligible, because most of the colleges in India demand a minimum of 55%-60% and you have scored good percentage, so you can get admission.

B.Sc in information technology and BCA, that is Bachelor's of computer applications are the popular computer courses, and if you are asking about short term courses then it depends on what you want to pursue after that in you graduation.

You can get this college directly there is no exam in modern college. Reference- https://www.shiksha.com/it-software/course/b-c-a-modern-college-of-arts-science-and-commerce-progressive-education-society-shivaji-nagar-pune-204173.

Fees in Institute of Management Studies, Saharanpur - Bachelor of Computer Application(BCA) is Rs, 60,000 per year.

Don't feel regretful. You have other options available also. You can pursue your BCA from other good university too. It can save your year. All the best for your future.

Plz follow the link :
https://www.shiksha.com/university/ipu-guru-gobind-singh-indraprastha-university-ggsipu-delhi-24725

no;IEMJEE is not mandatory to study BCA

If you crack the UPSC, you have a chance of being a part of the civil services of the country. These are 'A' grade services and officer are held in high esteem as they serve the nation and their actions are one of national importance. Even if you have done your BCA and have a good aptitude and a will to work hard, you should do well in the UPSC exams.

To switch your stream, you have to give particular subject entrance. Like in GATE to switch branches the respective branch exam should be given in order to pursue Masters in that. I hope you got the idea.