We recommend using two screws, each one 1.5 inches from the two sides of the board.
No, we do not recommend screwing through the UH02 boards, using composite screws or otherwise, as this would create cracks in the future. Therefore, doing so voids the warranty.
If using NewTechWood Starborn deck screws, you would not need to. Pre-drilling is required, if you use another brand, especially if you notice mushrooming.