Mark Hall has an idea for redeveloping the site of the Oakland Coliseum. But, perhaps most importantly, he also has a track record. Hall, the president and CEO of Hall Equities Group of Walnut Creek, has outlined a plan to pay $85 million for 44 acres, including Oracle Arena, of the Coliseum complex and turn it into a 15,000- to 18,000-seat stadium for a United Soccer League franchise, a centerpiece for youth sports tournaments, hotels, restaurants and retail. According to Hall's plan, there's...