The Sith Library has the location of Courscant, does that mean it can only be played if the "heart of the empire" is in play? Does it get played ON the heart of the empire? I guess the same question would go for the Dagobah locations and enhancement cards?

Or does the type just exist incase something will affect anything labled courscant/dagobah?

It is just a label.

Traits have no effect on any gameplay rules at all. Their only use is that they may be referenced / used by card effects. In which case, the card effects will tell you what you need to know. Until then, you can ignore them.