Re: First ? Erm ...
"it hopes to, for the first time ever, launch a commercial satellite into orbit using a previously used rocket."
Didn't the Space Shuttle used pre-loved rocket boosters, making this statement incorrect ?
The SRB's in the shuttle were essentially huuuuge fireworks with no control over throttling (other than the shape of the solid fuel - it had a star-shaped cross section, and was designed so that the surface area changed during the burn to adjust the amount of thrust produced), however a rocket engine has thousands of separate parts, and can control the thrust. Whilst SpaceX's rocket engines are in principle similar to the shuttle main engines (if you squint a bit), the shuttle was a very different beast to a rocket, and so the original statement is true.