And I claim it's an arbitrary distinction with no hard division. Is something I see directly observed? What if I see it through a window? What about on television? What if I see it through a curved window (a lens) that distorts or enlarges it? What if I see it through a set of such lenses (a telescope or microscope)? What if that allows seeing detail that I would otherwise be unable to see? What if I wouldn't be able to see it at all without the device? What if the light it emits isn't in the visible spectrum, but in infrared, and I need to use a device that converts that to visible light? What if it's emits primarily radio waves, and I use a computer to translate that into a false-color image? What if it's emitting Cerenkov radiation, and I use a computer to reconstruct its trajectory? Where exactly was the dividing line between direct and indirect observation?

I'm not certain I'd agree with that; some may simply be hard-wired to respond in certain ways, and I'd hardly call that a sense of self, but that's a peripheral issue. But if they do possess a sense of their surroundings, then the same caveat applies. All any creature directly experiences is its perceptions, and the brain uses that to create a model of the external world. It remains an assumption (albeit a very well supported one) that the external world actually exists at all.

I'm not sure I accept that either. Ever see a baby yanking on its own hair, but crying because it hurts? The perception is all there. The baby can sense the position of the hand, can feel the hair in her fingers, can experience the pain of having her hair pulled, but has yet to be able to understand that these are external features of the world over which she has control, and that she can get the pain to stop by opening her tightly-clenched fingers. Animals learn to model the outside world, and it seems that the more complex a model they form, the longer it takes to do so.

But again, all of this is really peripheral. I'm willing to grant the existence of external objects. And even if there are some that we can't perceive, that doesn't change the fact that there are things which exist.

Yes. As Cougar and I pointed out, the universe just consists of everything that exists. As long as we can confirm that at least something exists, there's a universe, consisting of those things. And possibly others, of course, whose existence we cannot or have not yet confirmed, so our understanding of the universe is likely limited or imperfect. But we certainly don't need to understand something perfectly or completely in order to be sure of its existence.