It seems to me that the idea is that the library stores" templates " of tools, and in the project you use the one that is available and adjust the tool parameters.
1. would it be possible to open the color palette rather than having a fixed color on the code ?
This is possible, but you need to write an appropriate program that will display a dialog box for selecting a color.
As far as I know, you can't do this with NX, but you can to use Windows Dialogs...