Do I need to connect "active low"?
The interrupt is an output, hence the "O" on the datasheet. It is open-drain active low so connecting it to ground will not cause harm. 



The purpose and function of the interrupt output is fully explained on page 9, and I don't see any purpose in repeating it here. It's intended to connect to an interrupt input on your microcontroller, with a pullup resistor to Vdd (since it's the drain of an n-channel MOSFET).