BCA

Usually, courses like BCA and B.Sc. IT require 12th with Mathematics. Few institutes also enroll just Science students. If you have not studied maths in 12th, then few institutes have provision for it too. You need to checkout the colleges where you are planning to apply. You will get a much better idea then.
All the best.

Visit the below link provided for getting all the details:
https://www.shiksha.com/it-software/colleges/bca-colleges-Mumbai-all.

See, for ethical hacking course, you can do from anywhere in India or from online programs. It's not the big deal if you want to get into this, then I'll prefer you to opt for the B.Tech from CS branch.

From my opinion, you have to opt for MCA.
But after graduation, the best short-term course is
G- CAT master (Graphiti School of Animation)
Duration= 12 months
Eligibility= You should be graduate

Please mention the college where you wish to apply.

Well, the rules are different for different colleges/university. If you have a backlog in the 3rd semester, you can definitely appear for the 4th semester because to clear the backlog of 3rd semester, you will get a chance in the 5th semester only.

If you had maths in your 12th standard then you can go for BCA because maths is the main subject in that.

Getting a good job depends on your skills and profile. Yes, college matters for the sake of learning and placement, but a good student will get a good job even if he or she studied in a small college. Also, if you are planning to do BCA then checkout other equivalent courses like B.Sc, IT/CS.
All the best.

Please check college website as the fee structure might be revised for the coming academic year. You can find more details about the college at https://www.shiksha.com/it-software/course/bachelor-of-computer-applications-national-college-basavanagudi-basavanagudi-bangalore-321531