I have a few questions about when a Quasar cannon fires. I know:

sector shot fires once on each planet when someone enters the sector. It also fires if they try to escape and they are interdicted.

the cannon fires once when they enter the atmosphere and once after the opponet destroyes the shield.

My questions are does the quasar cannon fire once after the offensive fighters are destroyed and does the sector shot fire when the attacking ship retreats from the planet? Also how much fuel does it require for a planetary interdictor generator to hold a ship in the sector?

Thanks