Torx 6-Lobe Pan Head Machine Screws are used because of the unconventional and efficient drive style. The Torx 6 Lobe drive style is designed so that the driver will not slip out of the fastener recess during installation, since the driver is not inherently centered on the fastener. This creates a lesser chance of screw stripping as well as allowing for a higher torque installation. A benefit/disadvantage of non-typical fasteners (depending on your point of view) is that it can be more difficult for users of a device to disassemble it than if more-common head types were used, but Torx and other drivers are widely available.
Black Oxide is a chemical treatment to stainless steel fasteners to add corrosion and abrasion resistance, as well as a sleek black look. Black oxide fasteners are used commonly in applications such as knife builds, gun builds, and in the automotive industry on both cars and motorcycles.