Thermal paste, or some oily thermal interface material, is necessary because it fills in the microscopic imperfections that otherwise trap air particles between the CPU and the heatsink, preventing the CPU from properly cooling.
Suitable for cat5 and cat5e cable with 8p8c, 6p6c and 4p4c plugs functions : cut the wire by the blade near the handles. Shell the wire by the middle blade. Press the connector by the crimper.