[Radiant] Associating a field with each page

[Joe Lapp]

Hi everyone,

I'd like to create a set of pages having two fields per page: a body
and an image URL.  The layout will centrally control the positioning
and formatting of the image across all pages, which is why I don't
want to embed the image separately in each page.

How do I do this?  Do I manually create an "image" tab for each new
page, and then have my layout retrieve the URL from this image tab?
Adding the tab to the parent page doesn't result in the children
inheriting it.

Also, I assume that each tab correlates to a VARCHAR in the database.
Is there a more efficient way to do this?

Thanks!
~joe

P.S. I'm an experienced web/software developer, but new to both Ruby
and Radiant.