I would like to know why is not possible to change forest clipping planes when I set the Tree edit mode.
The camera clipping works in Custom Edit mode, but it is temporary disabled when editing trees, to allow modifying the hidden items. If not, the user could not see all the existing trees, which is not intuitive.
doesn't exist a near clipping plane but the far only.
Exists the density curve but I prefer a near clipping plane that hide the trees that I don't want to see near the camera.
Far clipping plane usually is used to limit the density on large areas. Near clipping plane has not sense in this case, this is the reason we don't included it.
every time I have to adjust parameters for every camera. I want that every camera hold its own Forest Pack parameters, for example fall-off, fov, density, etc.
Unfortunately would be very difficult to store local parameters for each one of the cameras. For this purpose, we added "Use Environment Range". It lets to use the camera's environment range as falloff values.
I think also is possible to use the new state sets of Max 2013 to get the behaviour that you need, although i have not checked it.
When I have a bunch of billboards them face the camera, but if the sun has parallel rays with the billboard we will get zero shadows.
Forest pack should use the same bill board figure and orient it facing the selected sun (light).
This functionality already exists in Forest. You must assign the main light to Shadows->Raytrace->Light, and use Forest Material in the billboards.
The following tutorial describes the different shadow modes available in Forest: http://www.itoosoft.com/forestpack/tutorials/tutorial_shadows.php
I don't understand why I can't use Forest Pack Pro to distribute my lamps along a road.
I donno if Rail-Clone tool supports groups.
Basically because a group would contain non-geometric objects (as lights), and unfortunately Max doesn't allow to instanciate them in the same way that geometry.