Las Vegas Review-Journal staffers expressed frustration Monday after New Media Investment Group, the company managing the newspaper, brought in a Rhode Island editor to help establish guidelines for how the paper covers itself, the latest twist in a nearly four-week drama inside Nevada’s largest media outlet. Yet even as management tried taking more control of how the paper reports on its own transactions and new owner, billionaire casino magnate Sheldon Adelson, features editor Stephanie Grimes opted for the level of transparency that’s come to be expected from the Review-Journal newsroom.