I would diffinately agree with your first proposition.
I don't see any reason to believe that the universe that we reside in is absolutely everything in "existence"
In the same way that fish swiming in a garden pond must realise that the pond that they are living in is not Everything.
I would be almost certain that there is more than just our universe, but what form it would take is impossible to say. Something entirely inconcievable I would imagine.
As for your second proposition, I find that harder to believe.
You claim that since matter and energy are interchangeble that they are in fact nothiness.
Matter is a form of energy. As such we are all constructed of energy, not nothingness. To say that we are constructed from nothingness doesn't really make any sense, due to the very definition of nothingness.
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