why is most things in the universe round or "spherical"?

individual stuff in the universe starts as gas or dust that gravity attracts toward the center of the mass. All of it is pulled in tight, and gets as close to the center as possible. This results in a shperical shape because the sphere has the smallest surface area to volume ratio.

Once 'things' get large enough, the force of their own gravity

will pull them into a roughly spherical shape.

The larger the object, the more perfect the sphere.

You mean stars, planets, that sort of thing? Big objects (things above a certain amount of mass, depending on what they're made of) have enough gravity to pull themselves into a sphere. That's why planets are always spherical, but small asteroids tend to be potato-shaped.

Almost all things in our universe are near 'spherical' because the gravity from objects all around them crush and condense them into spheres.

Because those round thing exist in the universe such as, planets or like our moon, they all have gravity and because of gravity pulling everything toward the centre of the planet that is y is round.

Because the universe is efficient, gravity or molecular surface tension force these things into a sphere because it is the smallest space they can take up.

The larger the mass of an object the less ridged it becomes, gravitational force of larger objects and empty space do a cosmic dance where they an object if lesser mass must abide by the larger forces

The force of gravity tends to try to squish things together. in a sphere things are always equally far away from each other, there are no corners; which wouldnt make sense.

If all the 'something' in an object is pulled towards its centre by gravity... guess what shape it has!

Uniontera number 9, hope it helps.

Existence is the time expressed by light itself. http://www.youtube.com/watch?v=MjmOw1Pnc4s