That error is a standard issue when working with templates, in most cases the error can be ignored.
This issue and other limitations to the Dreamweaver Template engine are one of the main reasons why we developed the Theme engine in Framework builder.
For more details on converting your template to a Theme, see the "How to convert your site from DWT-dependent to theme-based" tutorial in the Videos section of the Design Extender support page:
design-extender/
The custom search wizard is not intended to be reentrant, any changes you wish to make will need to be done directly in the code, though modifying the css.