[@Rhiannon]
Well for communication they could do sign language or write whatever they need to say down on a note or similar program for the vocally impaired. For physical communication without facial features they could just exaggerate their movements, like if they want to convey incredulity they could swing their head towards the person and stare at them.

Also you are kinda vague on the powers of witches, you say they can do things but a couple of examples would be helpful especially with Energy magic because all I know is that the tend to be unstable individuals.