I'm Very Confused Right Now

The universe is actually finite. It is still expanding, but with a finite amount of matter in it. There are between 10^20 and 10^25 stars in the whole universe, less than atoms in a grain of sand.

They're probably referring to the 15 billion light years of the known (visible) universe.

Nope, it's about the 40 to 50 billion light years radius of the known universe, which is very different from the observable universe. As the universe is only 13.8 billion years old, we can see nothing that is more than 13.8 billion light years away from us, but various calculations, taking into account the relative movement of stars, make it possible to have an estimate radius of 46 billion light years for the universe as a whole. Then, taking into account the density of stars and galaxies, you can give an estimation of the number of stars in the whole (observable and non-observable) universe.

Seeing as how pretty much all quantum physicists don't know what the hell is going on and will admit that they get 100 more questions for every 1 answer they get....I would say none of it makes sense. Which by the way is the best part :)

Yes. You've hit head your head right on the nail.

http://mylittlefacewhen.com/media/f/rsz/mlfw4965_small.jpg

If you can't handle this post then your brain might explode by the time you get to Doctor 12.