If a Mesh Light is applied to one instance of a component, it is automatically applied to all other instances as well. To apply it to a single instance of a component (out of many), first select the instance, right-click on it, choose Make Unique, and then apply the Mesh Light.
Special objects can be removed from geometry by double clicking on the group/component, selecting the special object's widget and then selecting the Erase option from the context menu (right-click to open the context menu).
Scene units in SketchUp are always calculated in inches.
