Mating probably takes place in December-March in the North Atlantic, birth takes place 12 months later off the SE coast of the United States.
Right whales eat copepods primarily.
Although copepods are so small that 1500-2000 can fit into a teaspoon, rights consume more than a ton a day. For more information, find Steven Katona's book on whales, dolphins, porpoises and seals in the North Atlantic, in your local library.