Hi Steven,
Yes, Register 107 bit D7 controls the user programmable function of the single pole filter for the ADC. You can also use the pre-programmed values in Register 12.
There is no internal data path from the ADC to the DAC. This can be done externally by tying Dout to Din or you can bypass the ADC and DAC by routing the PGA to the output mixers.
Bit Clock can be used for clocking.