automated fire & skyfire

[wako1302]

Am thinking of getting a vengeance weapon battery with the quad icarus lascannon upgrade to see if this will help with my lack of AA cover.

Special Rules
Sentry Defence System: A building with this special rule can use automated fire against enemy units, even if it is unoccupied. In addition, the enemy units can shoot at and charge a building with this special rule, even if it is unoccupied.

My questions are
1Does automated fire mean that you shoot at the nearest enemy or at any enemy with BS2.
2If it means at the nearest, if you have SKYFIRE can to choose to use it to shoot at the nearest flyer, rather than the nearest unit.