Hi Shimizu-san.
Q1, The sample rate will scale exactly from any MCLK value in the table. Just find the SR0-3 values you want to use in the table, divide the MCLK value by the given sample rate, this will give you the over-sample rate for these settings. Now you can divide any MCLK value by the over-sample rate to determine the sample rate with a different MCLK using the same setttings. Of course if CLKIN is MCLK/2 then the result will be 1/2.
Q2, In this case you can find all of the same values on page 29 in the first row under MCLK = 18.432 MHz so:
18.432 MHz / 96 kHz = 192 so if you change MCLK to 12.288 MHz/192 is Fs of 64 kHz and if CLKIN is /2 then you have 32 kHz. So the sample rate for Q2 is 32 kHz.
Best Regards,
dave