Pathfinder Unchained introduces rules for Lore skills, which overlap somewhat with the set of core Knowledge skills. I think Lore skills make a lot more sense, so will be making heavy use of them.
It's generally a Diplomacy DC 20 check to find out what someone has been asking questions about. When gathering, you can take a -1 penalty to your skill check for every +1 to the DC to uncover your queries.
Note that a Gather Information check can be used instead of most knowledge skills using Diplomacy, however this takes longer (at least an hour, maybe a day) and also lets people know that you're seeking out this information.
Knowledge (Local) will no longer provide any knowledge about the local area. It's primary purpose will be primarily three fold:
Knowledge (History) will provide broad knowledge of history about the Inner Sea, and can also be used when researching historical concepts in a library.
Knowledge (Geography) will be theoretical knowledge about the wilderness, and may often be combined with Survival. Geography will tell you where you are most likely to find a river, or which way will most likely take you to a pass through some mountains. Survival will tell you whether the river is safe to drink from, or how to survive a cold night in the mountains.
Knowledge (Engineering) will also provide useful knowledge about buildings. With it, you can determine the best way to break into (or out of) a house, where the family jewels are most likely to be located, and where secret doors and passages are most likely to be.
It can also be used to find your way around places such as sewers.
Breaking into buildings would also be covered by Profession: Burglary.
The following Lore skills will be common in the region the campaign is starting in. Any character can take any of the following skills as background skills from the start.
Generally, the broader the skill, the harder it is, or answers will be less specific.
General knowledge about the city. It is an umbrella skill for the other Magnimar lore skills. it gives a broad (but shallow) knowledge of Magnimar itself.
Lore about a particular district in Magnimar. These are: Alabaster, Beacon's Point, Capital, Dockway, Keystone, Lowcleft, Naos, Ordellia, Underbridge. These will generally give knowledge similar to that of Lore:Magnimar, but the DC is at least 5-10 lower within their speciality.
They can be used to know the local streets. A DC 15 check will allow you to know the layout of the local streets, and DC 20 knows specific information. Not sure how this would work in the game.
Knowledge about the various criminal organisations in and around Magnimar.
Knowledge about the nobles and aristocrats of Magnimar.