None of your questions can be answered by science. Science is a great tool, but can't answer "why" things are the way they are. Just be grateful it is not different, otherwise we wouldn't even be here to ask the questions.
Similarly, asking what happened before the big bang is meaningless. Stephen Hawking puts it beautifully:
Since events before the Big Bang have no observational consequences, one may as well cut them out of the theory, and say that time began at the Big Bang. Events before the Big Bang, are simply not defined, because there's no way one could measure what happened at them.
This doesn't mean you can't enjoy pondering these questions if that's what you want to do, but do so with full realization you're now in the realm of philosophy, religion, and mysticism - not science.