#5 is the nylon clutch fork pivot pin - this is what the clutch fork pivots on when the clutch pedal is depressed. It is made out of plastic and should be replaced whenever the clutch is replaced.
#6 is the spring clip that holds the clutch fork down on the pivot pin. It should normally not need to be replaced unless it is broken.
However, whenever replacing the clutch disk and throwout bearing, I also feel you should replace #1 - the pressure plate or diaphragm. The springs in the pressure plate wear out over time, increasing pedal effort and decreasing the holding pressure of the clutch. Most clutch kits you buy today include the pressure plate, but it's just something to verify before buying a specific kit.