Which clipper version are you using? Most of them are 16 bit MS-DOS character mode only, no GUI support.
Yes, you can get the structure of DBF files from the file itself. If you have a tool like ErWin, Visio, PowerDesigner, etc you can actually create a reasonably complete ER diagram.
There are a number of third party drivers that allow Clipper applications to use SQL data, but I've never seen a Clipper driver for MySQL.
-PatP