No, there's nothing scientific about the idea, "Phenomenon X was caused by nothing."In scientific terms it is possible the universe had a cause. In scientific terms it is possible the universe didn't have a cause.
Quite right. It must have been caused by something, scientifically speaking. This is the key point, in fact.We are in agreement that know one knows at this stage. If science is restricted to casual explanations in terms of casual chains then this automatically excludes the possibility that the universe was not caused by anything.
No it's not. It doesn't require you to believe in any particular metaphysic at all. And it doesn't specify what the "cause" in question has to be. You could be a Theist or a rank Materialist: it wouldn't change this principle. All you have to believe in is that things just don't happen without causes sufficient to explain them. That's pretty much common sense, I think, if nothing else...which was caused by that, which was caused by that and so on... is a metaphysical explanation for causation.
There's nothing spooky about it at all. It's an assumption we all live by every day. If you hear a loud noise suddenly, you look around for what caused it, don't you? If you see movement out of the corner of your eye, you turn your head to see what's making it. If you find a present on your doorstep, you wonder right away who put it there. We all know full well that things don't happen without a cause. We look for causes and we expect them. It's just life.