Please bear in mind that Autodesk invented the DWF format as a non-editable format to view an AutoCAD file. Anyone who creates a DWF file does so with the express purpose of preventing its import into other systems to edit or change the file.
DWF is Autodesk’s own PDF, so to speak. It is an imprecise format that gives an exact visual representation at the selected printer resolution, but intentionally does not provide precision geometry.
Since there are always hackers who want to crack file formats just for the sheer challenge of doing so, it is possible to find programs cracking DWF to convert it to an imprecise DXF or DWG format.
There are legitimate file viewers to see DWF files available on Windows only at Autodesk Design Review.
For iPads, iPhones and Android devices, TurboViewer is available free from TurboAPPS.
Previously the McDwiff file viewer was available for Mac but since Autodesk discontinued the Freewheel server in January 2014 McDwiff no longer works.