Phage

Not exactly. What many people call "space" is anything outside the atmosphere of the Earth, but in the terms of the universe it is an area in which things can exist. This space can be occupied by matter or other forms of energy, or it can be completely empty. Our universe is all the matter and energy that exist, and also all the empty space in which matter and energy can exist. We do not know if space is infinite or not because we have not found an edge, but it does seem to be getting larger. (I will talk about time later down.)

This is a good way to think of it in a general sense, but it is much more complex. Lets just say that the rate at which time passes is variable and relative to the observer.

Try to imagine a point rather than a 3 dimensional object. A point has no length, width, or depth at all. Think of a map grid; point (32,57) is infinitely small.

Negative on the last half of number 4; space itself was a single point. Length, width, and depth were meaningless because everything including the capacity to exist was all in the same place (all places were one). I cannot really comment about if atomic activity was stopped or not because pretty much all of our understanding of the universe today make no sense in that context.

Matter and energy did extend out, but space extended as well. Suddenly things could exist apart from each other. This can also be considered to be the start of time.

Scientists are talking about not only the matter and energy but also the capacity to exist that makes up our universe. There might be other universes "outside" our own but it would be a peculiar concept indeed.

I would like to make a simple analogy to better explain the concept of "space", as you seem to be thinking of it as merely a vacuum. Remember that a vacuum is "A space empty of matter".

Lets imagine a piece of paper, which for our example will be completely 2 dimensional (no thickness). On this paper we will draw a stick figure and let him explore the area. Soon enough he will come to an edge of the paper. Beyond the edge of the paper the capacity for drawn things to exist ceases. You are probably thinking of this piece of paper floating in the air somewhere or sitting on a table; you are still stuck thinking in a 3 dimensional context. Remember in our example I only defined the sheet of paper and outside the sheet of paper is truly nothing.

If you can begin to think in the terms of 2 dimensions then you can understand how hard it would be to add an unknown type of dimension to our 3D view. Scientists cannot disprove the possibility of other universes but they would be separated from us by an indescribable void and located in a manner which hurts my brain to think about.