Yes, absolutely.

Essentially, objects that move in a random direction scatter, as described on page 95. Such objects only move in the direction shown by the small arrow on the Hit icon if the rules tell you they do so. Otherwise, the object does not move.

Yes.

Apply unsaved wounds to a unit one at a time and one model at a time. When a model is reduced to zero Wounds on its profile, it is removed from play as a casualty (as described on page 102). If a model loses more Wounds than it has on its profile, the excess wounds are lost – they do not spill over onto other models in the same unit.

With this in mind, apply unsaved wounds that cause models to lose all of their remaining Wounds first (Killing Blows and Monster Slaying Blows, for example), then unsaved wounds that cause multiple Wounds to be lost (Multiple Wounds (X), for example), then, finally, unsaved wounds that cause a single Wound to be lost.

A Close Order unit always acts as such, even if it only contains a single model.

No. A unit cannot be obscured from the enemy by itself.