if u have no gp car on hand, recommend u buy NT1...
NT1 craftmanship and design is very good....nearly no weak point could be found in the chassis(except the front knuckle)
But if u have a GP car on hand, recommend u continue to play....Although NT1 is better than 3R and MTX4, the difference is not too big in track....In Shek Mun, many people change to play NT1. However, their speed didnt get fet faster after use of NT1....
The set up and your finger are more important than which chassis u ar going to drive
Regarding your first question, it is subject to personel preference....In the past, I tune no brake at neutral position...but now I am using little bit break at neutral position....