Creating external cameras is pretty easy, but will require you some time to do experiments before you could get a nice set of cameras.

Here are the required steps:
1) move in your model (as usual with arrows and CTRL) and decide where you want to locate your camera.
2) press on NEW to create a new camera
3) select min fov (field of view), max fov, and activation sector (see below). You can test fov settings with the button TEST
4) press SET. Note: if no camera is selected on the list the program will crash!



Activation sector:
Once the car hit the sector the camera will be activated.
To understand in which sector you are just press S on the track. It should be named like XXRoadXX

You can create even more than one camera for each sector. In this case the camera that is closer to the car will be activated.

Put 0 as activation sector if you want that your camera will be activated without a specific sector. In this case this camera will be activated when the car is closer than other cameras.


Camera movement:
Select Fixed if you want to have a fixed camera, otherwise your camera will follow the car using Min and Max Fov.


Interface:
Double clicking on one of cameras in the list you will load the settings and you will be positioned were your camera is.


Export:
To try your new cameras in nKPRO you need to create the file
{your track}cameras.nkc2




Thanks to Kunos and Si3v to help me out with this!

more informations to understand better how the cameras really work.

in each moment distances from the car and each camera are calculated using the following formula, and the camera with lowest distance is selected:
distance=500*(sectors_difference)+real_distance

where sectors_difference= camera_sector-car_sector

for example, if the car is running on sector 3 and a camera has as the activation sector=5, then the distance will be
distance=500*(5-3)+real_distance

The activation sector is used as a weighted multiplier.

Let's see a practical case:

car: orange box
cameras: in green and showing the activation sector
real distance car/camera in red.
track sector in white

In this case the camera 6 will be active since it has the minimum dist value.

Note how camera 3 and 5 at the same distance (1000) from the car have different value of dist. For this reason in case camera 6 wouldn't be there the camera 3 would have been selected.




One more trick: on the configuration file itself you can modify the MAXDIST of a camera. This value is the radius of the camera. If the car distance is bigger than the MAXDIST this camera will be ignored.


Here is the theory, so, you just have to do some experiments to have the effect what you want.
So, every camera setting depends on the camera itself but even on the surrounding camera. Just try it an let me know if you have anymore comments or tips.

It might happen a case like the following, where your car disappear from the screen.



I found out that this caused by a transparent object between the camera and the car. In this case it was a tree.

At the moment I haven't found any better solution than moving your camera in a different position, so that the transparent object will not interfere anymore.