1)The MIPI_RESET should be pulled down to ground using 10K resistor (as mentioned in the datasheet).
The CX3 chip will internally drive this pin high during power up. You don't need to connect any external component for the same.
2)By MIPI_CLK do you mean MCLK pin of CX3?
You can leave the MCLK and XSHUTDOWN pins floating when they are not used.