@OP
Most of your questions are valid, in some degree, from a scientific point of view. As you can see from the replies, some scientific theories can give you answers with more or less uncertainity.
The questions about what happened before the origin of the universe are very controversial in science because, at the current state of art, you can't answer them without a high degree of uncertainity.
However, all scientific theories work like this at the begining. When you collect more evidence to support your theory, the less uncertainity and the more it becomes accepted by the scientific community.
The reason why some scientists reject the hypothesis of God is in not because they are gnostic atheists, it's because this hypothesis lacks evidence from a scientific point of view.
If you assume a previously selected answer to be correct when all answers fail to meet scientific criteria (including your selected answer), you are commiting a confirmation bias. If you want to prove that the universe was created by God, you don't need to prove that all the other alternative hypothesis are wrong, since this will never prove that your hypothesis is correct, you just need to prove that your hypothesis is right.
The answer I would give to your questions is that we (humanity) don't know for sure, but some people are coming up with some interesting hypothesis supported by evidence.
If you want to belive in God just because it seems like the more reasonable hypothesis for you, that's fine. Science is not about searching for an ultimate truth, it's about searching for an explanation that is coherent with the evidence using the little information that we can gather.
Ps: It's normal to think that scientists just make things up when you don't know all the theoric framework and evidence that support their affirmations. In most cases, it's a good thing to be skeptic even to science. Just don't be a lazy skeptic who calls bs to everything you don't understand.
I know... my english sucks
