Newbie here:
When creating my own them, is it best to use a theme (as in the basic theme) and modify it? Renaming the Folder in case the theme is updated, as in Wordpress child theme?

A Worpress child theme needs a folder with only the files you want to change.
A custom Zenphoto theme usually starts with a full copy of a theme folder which you have to rename.
http://www.zenphoto.org/news/theming-tutorial/

Or directly spoken: Zenphoto does not have child theme functionality.

Thank You fretzi,

That answers my question, as I knew it did NOT have a child-theme, I wanted the best way to start my own.

been working on for a while.. now i have another question to post.

Thank You