You can import different file formats directly into a station without using the CAD converter. You will still need a license for the format though. The internal format is always .SAT so yes, the files are still converted.
Visualization formats such as VRML and STL can be used without an additional license.
When you use the CAD converter you have greater control over translation settings, and you can also export to IGES, STEP and VDAFS (if you have the license).