A1: SCK must be on all the time. It is clearly stated on page 17. It is also required for the I2C control interface. See page 25, noise suppression on the control interface - this requires the system clock. Furthermore, the frequency of SCK determines the maximum speed of the I2C interface (see Table 2, footnote 1). The part will not work correctly, if you remove SCK.
A2: We will update the data sheet if there is a confirmed error in the data sheet.