Those questions are irrelevant to multiverse hypothesis because they apply to any theory. That is, if there is no multiverse, you can still ask "Who/what created the universe? Do matter and energy simply exist without creation?", etc.

Do matter and energy simply exist without creation?

It depends on your definition of "creator" but indeed it is almost a logical necessity for something to exist without a creator. Since if you assume a creator is necessary, you'd still need someone to create the creator, and so on going infinitely. And then there's the question of creation of this infinite chain itself, etc -- the recursion never ends. It seems much more simple to assume some system must simply exist without necessity of creation.