The general direction may be possible, but the source itself would not be. The compression is smallest parallel to the direction of the wave's travel, and is largest perpendicular to the direction of the wave's travel. LIGO measures a change in the difference between the lengths of the two arms, ad so it would be more sensitive to waves moving along one of the arms. It would not be at all sensitive to waves that are moving perpendicular to both arms.

Since there are two such facilities, located on different parts of the Earth, they may be able to compare the relative size measured by each facility, and narrow down a part of the sky. Since the facilities are relatively close to each other (only 2000 miles, 30 degrees along Earth's circumference), the margin of error would be very large.

Ideally, to localize the direction, you would have three facilities, each located at 90 degrees away from the other two, so that you have one facility "pointed" in each direction. Even then, it would only be able to narrow it down to 2 possible origins, as the direction of travel of the wave would not be measurable.

Anything that carries information is limited to the speed of light. Gravitational waves carry information about the location of the merging black holes, and so they are limited to the speed of light. If anything that carried information were to travel faster than the speed of light, it would break causality, because you could find some frame of reference in which the effect happened before the cause.

And yes, it is spacetime itself that is vibrating.