What can we do with it? Well, we might be able to use it to prop open wormhole mouths.
*cough*cold-fusion*cough*
Not at all comparable. This group was headed by a Harvard-Smithsonian researcher, and their results have been peer reviewed.
Plus, the entire problem with cold fusion is that it can't be replicated. These observations can and have been.
Dark energy = ?
I think somebody couldn't remember whether he was talking about "Dark matter" or "Negative energy" and ended up making up something. Cuz I've never heard of it before.
They are different and distinct. Dark energy makes up a large chunk of the universe, larger than dark matter. It's a repulsive force, homogeneous throughout space, that seems to function as a kind of antigravity.