CBSE 12th

Yes, you need a migration certificate.

No its cmpltly based on your hard work and your concepts that your learnt in class 12th. Because level is little bit tough btw uhh need practise. If uhh do this uhh didnot find any difficulty to clear your semesters.yess bcom honors accounts is little bit different from the 12th class accounts btw if learn the basic concepts uhh did not find any difficulty in them.best off luck for ur future

Yes you can, but it's better that one of the courses will be done in correspondence, because you can't attend both courses lectures/classes at a time.

You will easily get a seat in one of the NITs with higher rank with CSE stream. Kindly fill the counselling form according to your preferences. Moreover, you'll get one definitely in Surathkal, Rourkela, Warangal and Trichy.

You can again fill the form with a new email ID.

If you have Biology as your main subject, you may go for B.Sc. Biology.
Else, pursue other subjects which you think you are good at.
Never get dejected.

Lucent general knowledge books.

It is possible if you go for private university, but for government or aided, it's way too hard.