The Great Wall isn't wide enough to be seen from space. There are a few objects that can be seen from low orbit but this isn't one of them.
If you were exposed to the vacuum of space, you'd die in less than two minutes. During that time you'd experience some bloating, but no exploding.
The popular image of an asteroid belt is that there are millions of huge rocks floating within metres of each other. In movies such as The Empire Strikes Back, it's shown to be an incredibly dangerous place for a spaceship. In reality it's not like that—although asteroid belts are relatively dense compared to the rest of space, if you were standing on an asteroid you probably couldn't even see any others because they'd be so far away. Spacecraft have passed through our own Asteroid belt many times without any problems.
Actually they're barely warm and quite safe to touch.
Black holes have gravitational properties just like everything else—no worse. If our Sun was replaced with a black hole of the exact same mass, all the planets would continue to orbit in exactly the same way.
The Sun does appear to be yellow from the surface of the Earth, but that's because of light scattering in our atmosphere. From space it looks white.
At any one time, half of the Moon is in shadow and half of it is in sunshine, just like on Earth. However there is no permanent dark side of the Moon any more than there is a permanent dark side of the Earth. When referring to the side of the Moon we can't see, it's better to call it the far side of the Moon, as it's not necessarily dark at all.