Does the square edge board let me cut it at any point to get the lengths I want while still seeing a solid edge, or does it have a hollow interior?

Hello, thank you for your interest in Trex! Yes, our boards are solid throughout so you can cut to any length and the end of the board will still look the same as it does to begin with. Our Enhance boards do have the scalloped bottom, but those scallops are also solid throughout. Hope that helps! If you have any additional questions, feel free to reach out to our Customer Care Team 1-800-289-8739.