Why does it sometimes say 'DX8' within the user interface and the code?

Site Studio used to be called DX8. When it was changed to Site Studio, some machine names that were core to the system couldn't be changed. Apart from making the naming within the code a little less consistent, it shouldn't cause you any problems.

Site Studio has existed for many years before it was released as a product. It was previously called DX8. For this reason, the name DX8 occurs within the code. Unfortunately we were not able to change all instances of the word DX8 to Site Studio without causing backwards compatibility problems for existing customers. Apart from making the naming within the code a little less consistent, it shouldn't cause you any problems.