San Diego-based Price Co. finalized its joint-venture agreement with Montreal-based Steinberg Inc. to open a Price Club Warehouse store in Canada early next year . . . Castle U.S. Corp. announced that it has signed a letter of intent to exchange an unspecified number of its shares for all of the stock of Los Angeles-based Intervideo Network Inc., a privately held California corporation . . . Moody's Investors Service said it has confirmed Fluor Corp.'s Baa2 senior-debt rating and its prime 2 rating for commercial paper . . . B. F. Goodrich Co. said it will establish a new plant at Norwood, N.C., to manufacture aircraft tires.