Modify OpenSource C# project to add functionalities (Google Earth Plugin)

For this project [login to view URL] I need add functionalities. I need in easy way add a Placemark, each Placemark wil have a Name + Comments (will be nice select sketchup models for the placemark, we can store 4 models to use) I need for each Placemark Store the distance for the 3 more next Placemarks, You can use Ruler to get that. I need get all info about visibility between 2 points, Its for telecomunication then I need check altitude to avoid objects between the points. If two points have good visibility you can mark that with a color, for points with problems of visibility (hills or mountains between) you can mark it with red color or something like that...visible. The information to the next points will be stored in the comments of the placemark. I want it as easy as possible, graphical & friendly I need add,edit & delete placemarks. Add the data about distance & altitude to imported kml files is important Say "Hello eduardb" if you understood everything.