How was the Apollo Command Module physically connected to the Service Module (and the rest of the Saturn V rocket) via umbilicals (that housed electrical cables to initiate the burn of the SPS engine, plumbing, etc.) in such a way that the integrity of the heat shield was maintained (i.e. no "holes" in the heat shield) ? Were umbilicals that were external to the actual Command Module used ... and, if so, how were these severed/disconnected before reentry to earth ?
Thanks !