It helps me remove my bias- I still monitor all the other indexes how it is like ES, YM, and RTY....but NQ is my main instrument and I like to flip the chart when trading it so I have a neutral bias and trade what the market tells me to do.
In regards to your other question, I think actual volatility. Large moves when a setup occurs instead of chop to a billion pieces. I dont mind if it's a doji type of day as long as moves are violent and large.