I notice in the Blog instructions it says if you have altered the page colours etc to ask for a "duplicate"page -- but thats not useful on the rest of a web site
Unfortunately that's not possible in iWeb.
For the iWebFAQ website I took a Blank White page and changed the background size etc. I then duplicated it for the other pages.
If I want to add a Welcome, About Me, Photos or a Movie page I select all, copy and paste it onto my blank page.
That doesn't work for My Albums pages, Blogs and Podcasts. For those pages you have to re-apply the settings manually and then duplicate the entries.