Cant, to legally drive the car you must be insured, basically you can insure a car against multiple names.
So car 1, 2, 3 and so on can have both owners in terms of insurance. What you do is you specify 1 owner, and the rest you specify as co owner/driver, basically you are just insuring the car to be driven by someone else. But the owner of the car must be insured, otherwise he cannot drive the car.

So to answer the question no you cant, but you will find it problematic when you try to get it insured as you would be insuring yourself as the co owner/driver but to do that the car would need an owner insured first.

Yes, you can change ownership to get NCD from Car 2  for your new car but troublesome. To change ownership you need to send the car for Puspakom inspection. Any tinting which doesn't comply must remove. Then the road tax and insurance will be cancelled and need to buy again under new owner's name.

It is better to buy your new car under Owner B's name to enjoy the NCB from car 2. I presume B is your spouse so for loan purpose you can be the guarantor so the bank consider the combined income instead of only B's income. This is applicable only for husband-wife and parent-child relationship.

As said above, NCD is attached to the name not the car. What you can do is either:
a)Buy new car under B's name.
or, slightly more work:
b)Transfer car A to B's name, then A buy new car, carry over NCD to respective cars.