4. "I don't know much about these files but" In response to In response to 3
"However you can import your FBX into 3DS Max and re-export it out as a DWG or DXF. Revit will then be able to import the file. Even better news - NavisWorks will do it directly for you. Just go into Append and FBX is one of the options offered." found this online after googling