BCA

It depends on in which Institute you do your BCA. If you do in top Tier I Institutes then you can expect 100% placements, if not you cannot. Rather than just stopping with BCA. I suggest you to go with MCA too as it helps you get placed in Top Industries. For top Institutes, check the link;
https://www.shiksha.com/it-software/ranking/top-bca-colleges-in-india/96-2-0-0-0.

According to previous year cutoff, ,there is very less chance of getting the same.

Please use JEE Mains college predictor to know the chance of getting the college
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor&ved=2ahUKEwj3xNeLyariAhVFVH0KHSMiBDwQFjAAegQIARAB&usg=AOvVaw1N9BzFtyUCP4JU-2UQHQ0H

BCA is a good option, but as you belongs to commerce so think about it properly. Have a look to the subjects because it is totally different. Then decide.

Check the scholarship eligibility and then compare that whether you are eligible or not, as simple as that.

Being a Graduate degree you can pursue, it in Chennai itself as many North Indian students are studying here and cost of Living is also cheaper to other states.

Place of study does not matter. If you want to a Computer Science Engineer then Pursue BE (Computer Science Engineering) - Four Years Duration Course. BCA is a Humanities Degree in Computer Applications which will gives you knowledge.

Yes, you can do MS from Canada. You are eligible for the same. Good luck.

Computer Science is the best option in this line of your choice with specialized courses in internet security and more.