Phoebe and Piper seem at a loss when trying to find Prue, but they have the ability to scry and have used scrying in the past to successfully find a witch.
Piper (14:24) tells Leo she couldn't find the weapon in the Book of Shadows anywhere, 2 minutes later she is looking at the Book of Shadows and the weapon. 3 minutes later she tells Darryl, 'No, still looking.'
Phoebe points to lot 827 and says it's at the top of the hill. The map she is looking at doesn't show the terrain, just that the lot is at the end of a cul-de-sac.