On the first issue, the random effector needs to be included in the Effectors list of the cloner. If the cloner is selected in the Objects list when you add the random effector it will automatically be placed in the cloner’s Effectors list. If the cloner is not selected when you add the effector, the effector will be added to the Objects menu but not automatically linked to the cloner. In that case, which is most likely what happened with you, you need to drag it in there manually. In either case, the random effector will appear above the cloner in the Objects menu when it is added, but may or may not be in the cloner’s Effectors list.
Concerning the material issue, do you have a display tag on that object? It would be helpful if you could post the project file.