More puzzles about Star Wars VII (spoiler alert).

When Leia meets Finn, she says she’s desperate for any information on the Resistance super weapon–Star Killer Base. Not too long after that, though, she is handed a report indicating that the super weapon is being charged and that her Resistance base is the target. So, how did the Resistance find out they were the target? That presumably would not be revealed by scanning the planet. Must have spies on site, with access to the super weapon’s targeting software. But, then, why was it that just a bit earlier, Leia was desperate for any knowledge Finn had about the weapon?