BCA

No, you must have a science subject in your 12th to pursue the BCA as it is a computer oriented course which contains the subject of programming language as well as maths also.

Please refer the link to know the detailed eligibility criteria https://www.shiksha.com/it-software/course/bachelor-of-computer-application-st-xavier-s-college-ahmedabad-navrangpura-284239. The forms will be out in the month of May.

Hi, Admission in the above college is based on the marks obtained in 10+2 or equivalent. https://www.shiksha.com/it-software/course/bachelor-of-computer-application-dav-college-Chandigarh-247354
Please refer to the link below for more details on admission:
https://davchd.ac.in/ContentPage.aspx?Id=1648mJoc52bRWS76jCzLmf5o3y/8ZdIbqGbUwCOB+H48fs=
You can download the prospectus. Thanks.

I won't give a list here. But I would suggest always aim for high. The colleges :
IITs. NITs. BITS Pilani
BIT Mesra
IIIT ( Indian institute ) avoid new IIITs
IIIT ( International institute) Hyderabad, Bangalore (Dual Degree ) are the best. These list are the best. No other colleges can beat these colleges as they are the brand names. Always aim for the central funded government colleges like the ones mentioned above. Though I have listed some private colleges but they are the best one can say.
Good luck.

You can go for highly study like you can do MCA, MBA, etc. Or if you don't wanna to study now you can do job also by cracking interview of many companies like HCL, Wipro Infotech Ltd, etc.

Yes, depends on the programme and university admission requirements. It may be difficult to apply to US and Canada since you have a 3 year degree. Just check admission requirements, course requirements and proceed accordingly.

It's going to be difficult, since its not relevant to your prior academic background. Yes, you can look for Diploma or pathway courses or any foundation pre-requisite courses. You have to communicate with the colleges directly. Write to them.

For admission in BCA, you need to have 10+2 years of schooling from a recognized board CBSE or equivalent.

Which course are you asking for? Some courses take admission on the basis of merit, others through entrance exam.

This college is good when it comes about placement, but the main thing which matters the most in computer programming and application is about your passion and interest.
If you want to take admission in this college it is centralized (DAV College). - Forms come out in May.
Best of Luck.