Donald R. Diamond, a wealthy Arizona real estate developer, was racing to snap up a stretch of virgin California coast freed by the closing of an Army base a decade ago when he turned to an old friend, Senator John McCain. ...Courting local officials and potential partners, Mr. Diamond’s team promised that he could “help get through some of the red tape in dealing with the Department of the Army” because Mr. Diamond “has been very active with Senator McCain,” a partner said in a deposition. ... A longtime political patron, Mr. Diamond is one of the elite fund-raisers Mr....