Kinetic blast is not a 4th level or lower touch range spell, it is a class ability of the Kineticiest. Spectral Hand is specific in that it allows you to deliver touch range spells of 4th level or lower. Kinetic blast has a range of 30 feet not touch. So, spectral hand cannot deliver a kinetic blast.
Detached hand is being controlled by the possessing spirit not your character. It acts as a familiar but does not gain all the ability of a familiar. It specifically states it does not gain the deliver touch spells or share spell abilities. Furthermore, the feat specifies you cannot use the hand while removed. That last part would prevent you from using it with kinetic blast or anything else for that matter. The controlling spirit is using the hand so it can do things with it not your character.