My understanding of how this works is

Walls.
When a wall is destroyed a broken wall counter is placed either side of the destroyed wall.

Elevated Terrain
This can never be destroyed.

Indoor Blocking Terrain
Not a wall so something like the trophy cabinets in the new Batcave Map. These are not elevated terrain (there can never be any elevated terrain indoors-I think) so these can be destroyed. A single square is destroyed per attack and is replaced by a single rubble counter.

Destroying such indoor terrain would be a good way of creating hindering terrain for a stealthed figure to hide in.

Is the above correct?

Well...

Yes, regular Elevated Terrain cannot be destroyed. You can't blow the side off of a building.

But, Elevated Blocking Terrain (the AC units and such on top of the building) can be destroyed.

Great.- (forgot about those confusing AC units)

The rule I was most unsure of was destroying indoor blocking terrain such as the 4 squares of Bat Computer in the Bat Cave Map.

In a recent game I was unsure as to wether I could destroy a square to get line of sight and then use it as hindering terrain to hide in.

Yes you can. Perfectly legit.