For general purpose use point angle of twist drill is 118 Degree.
The process of enlarging the end of a hole to an even depth for housing the socket screw head is called as counter boring.
A jig is a work-holding device that holds, supports, and locates the workpiece and guides the one or more tools to perform a specific operation.
A fixture is a work-holding device that only holds, supports, and locates the workpiece, but does not guide the tools to perform a specific operation.