Hi grega1

It seems that you are creating your own troubles.

1.If you want to personalize a category of your site
the module Pico will allow you to wrap or overwrite
your theme header metas, stylesheet, ajax, etc. Also
set permissions by user. There's a lot of freedom!

2. You can clone your default template set and modify
to match your site design.

If you decide to run xoops.org release, you will find
the information you need visiting the official doc-faq

Have Fun !