Hilton Plans South Africa Hotel/Casino: The Beverly Hills-based company said it signed a preliminary agreement to develop the 500-room facility with a large South African company. The casino, which will have 75,000 to 100,000 square feet of gambling space, will be built between Pretoria and Johannesburg and will probably open in the first half of 1998. Hilton Hotels Corp. Executive Vice President F. Michael O'Brien declined to disclose the South African partner's name or the amount of Hilton's investment. The company expects to make a formal announcement in a few days, he said. While casino gambling is currently illegal in South Africa outside of the country's tribal homelands, most South African provinces support legalization and O'Brien said approval is "imminent."