Answered on January 20,2020
NOC won't work because the NOC got expired as it has a validity of only 6 months. As per Bangalore RTO, the vehicle doesn't belong to them now. So you need to get NOC canceled and get a new NOC issued.
Fine would be a nominal amount. The major amount would be the road tax, that needs to be paid at Bihar RTO. Road tax depends on many factors and the age of the vehicle is one among it. So older your vehicle, lesser the road tax needs to be paid.
You can get road tax refund from Bangalore RTO, once you have registered your vehicle at Bihar RTO.
There is no specified time limit for the same. Some people has got it in 3 months and some have got it after 1 year. During this period, you can track the status of your payment by filing RTI (Right to Information).