Buddha tells that everything originates from nothingness, emptiness, sunyata.
First, emptiness is not nothingness. Depending on the school of Tenets, emptiness refers to the absence of true existence, or to the absence of inherent existence, or to the absence of self-sufficient substantial existence, or to the absence of external establishment.
Second, emptiness cannot be a cause because a cause must preceed its effect, while emptiness and its basis (i.e. the object that is empty) arise, abide, cease simultaneously.
Third, emptiness cannot be a cause because emptiness is permanent and permanent phenomena do not perform a function.
The only context I know of where we find the expression, "phenomena arise from emptiness" is Tantra. In such a context, emptiness does not refer to emptiness itself, but to the mind realizing emptiness. This mind arises in this or that aspect.
How can something come from nothing.
It does not. Phenomena are produced by other phenomena.
Space, time and matter/energy is just and illusion.
Usually, we say that phenomena are "like an illusion", not that they are illusions. If you happen to read a traditional text that says that "phenomena are illusions", it means that they are "like an illusion." What we mean by this is that they do not exist the way they appear.
'Energy' is a word I never came across in any traditional text. However, we speak of 'matter' or 'form'. All objects that are apprehended by sense consciousnesses are 'matter'. This include smell, sound, taste, etc.