The fifth position puts the two pickups in series for a hotter sound. The 0.005uF capacitor is the tone switch. The higher the value, the more high frequencies it rolls off and the mellower the sound. Try 0.01uF or even 0.02uF for a really deep tone. The l500pF capacitor increases the proportion of high frequencies as you turn down the volume control, creating a brighter sound for rhythm parts.
Smaller values have less effect.