Most of the time it's an Int'l config 763. It's possible that it could be an XM'd plane, but there's no way of knowing that this far in advance. It's really a short flight, so the old 763s should be just fine.

As far as seats are concerned, my preference is for 3D/F or somewhere in the middle, because both of you have an aisle. But if you're travelling together that doesn't matter as much. Only other thing to take into account is that they usually start serving from the back in a horseshoe, starting on the A side.