Hi,
To import CAD files you will need to save them as DXF files and you'll need to upgrade to the Punch AS 18 package (the only with DXF import capability).
After you import the 2D file, you'll need to convert the pieces into walls, windows, etc, and then you'll be able to see them in 3D, add textures, plants, etc. The CAD features in AS 18 are improved, and yes, you can snap.
I never heard about Autocad 2001 version (I know Autocad 2000, 2000i, 2002 and 2004), but anyway DWG is the native Autocad format, and the DXF conversion can be done from any version (The DXF version is R12)
I will be glad to help if you need more information
Regards,
Patricia