We just bought 720 ft of an engineered wood floor and we are trying to decide how to install it, either glue or staple. The floor is 3/8" tongue and groove and will be installed on the second floor of our house on top of 3/4" plywood. The flooring will be installed across the joists rather than parallel to them. Any opinions on which is a better installation? Do I need to put in a sound barrier?