CBSE

If you want to pursue B.Tech then improve your mathematics. Because mathematics is common for all discipline in initial semesters of engineering. You can keep practicing mathematics problems in XI and XII. It's not at all very tough, but you can easily tackle it with proper planning.

Yes, you can get admission.

Yes and they are available till 7th November.

Its possible, march ahead.

Hello, VITEEE is going to be held in April 2017. You can fill in the name of school from which you first appeared for 12th, along with roll no.

No, it is not necessary. You can complete your HSC education from any recognised board.

CBSE is a board which is known and acknowledged not only in India but abroad too. Studying from Punjab board may not pose a problem in India but in Canada it will.

No, you will never face any problem in future.

I am afraid you cannot. The registration for the board exams are already done, and you are allotted a certain registration number. Changing school would mean change in registration number as well.

You will need above 75% so that you have a better chance to get placed in a good college or in a top NIT.