Would a human body decompose in space?

Yes.

But at a much slower rate and from forces not normally noticed having an impact here on earth.

The second law of thermodynamics holds that all things progress toward disorder. The third law provides a sort of exception at absolute zero. However, in your example the body would not necessarily always be at absolute zero. In fact the subtile stresses on the corpse from uneven heating from the sun and stars would assist a break down. This is similar to the way water cracks up concrete by freezing and thawing in the cracks. In your space corpse example this would happen very slowly, but still happen. Heat, cosmic radiation, asteroids, comets, gravity et cetera would all be working on the dead body.

But, yes eventually those ordered atoms in the body would progress toward disorder and break down.

It wouldn't rot per se. It would be likely, though, that it would eventually be overwhelmed by the gravity of some large body and be destroyed that way.

Not decompose in the sense of rotting. More likely it would dry out and become mummified.

nope, theres no oxygen to allow bacterias to decompose it