The location spaces have two icons, on the lower left and right. What do they stand for, what items you tend to earn in location encounters? And why are some inverted in color (white and black versus black and white)?
Yes, those are things that are more likely to come up in encounters there. It's no guarantee, though. This is described in detail in the rules in the section titled "Location Icons" on the last page of the rules, along with a lot of other helpful summary information. The key part is:
Each location on the map also has several icons associated with it. These icons tell the players the most likely outcomes they can expect when they go to that location.
Note that they're just the most common. Other rewards are possible as well, as are all kinds of nasty stuff.
The inverted ones are things you can get by using the special encounter at the location. They're still more likely to come from encounters as well. For example, the Curiositie Shoppe has an inverted unique item icon, reminding you that you can purchase unique items there, and they're also possible to get from encounters.
Some locations have special location icons that have their colors reversed, such as the Sanity icon on Arkham Asylum. These icons indicate that there is a guaranteed method of acquiring the described item at that location.