Ok, I know, I should have done the intermittent upgrades, but I didn't. I plan to upgrade manually so that if something is amiss I can go back to 3.7.3 until I figure out what to do.

I see in another post that it might be better to do the upgrades in stages ( http://forum.bytesforall.com/showthread.php?t=21394 ) - that was 2.6 to 3.7.13, although some versions were skipped, including 3.7.3.

Do I also need to do this process going from 3.7.3 to 3.7.15 in steps, rather than going directly from 3.7.3 to 3.7.15?

Once I get it up-to-date I plan to put my header images, logo and favicon in the new image location as per Juggledad's instructions (in http://forum.bytesforall.com/showthread.php?t=8520).

I am also curious about Juggledad's new note at the top:

=========================
As of 3.7.12 I recommend putting the header images. Logo and Favicon in an external file - using the new 'Image Locations' option - and then doing automatic upgrades (after doing a backup of course).
=========================

it seems to contradict what is said in step 1 of the instructions, and I'm wondering why the change.

Anyway, as always, thanks for any help you can give! And now that I have a bit more confidence about updates I'll keep up with them!

A question first... I your current version of Atahualpa in a folder called atahualpa or is it in a folder called atahualpa373 or something of that sort?

Just the plain default "atahualpa", as it was an automatic install rather than a manual one. And in case you need to know, I just upgraded the site to Wordpress 3.9, and updated all the plugins.

I am also curious about Juggledad's new note at the top:

=========================
As of 3.7.12 I recommend putting the header images. Logo and Favicon in an external file - using the new 'Image Locations' option - and then doing automatic upgrades (after doing a backup of course).
=========================

it seems to contradict what is said in step 1 of the instructions, and I'm wondering why the change.

The reason for the change is a change in WordPress rules. It use o be that you could not have any file/image used by a theme outside the theme folder. And that ment each time the theme was updated your images were wiped out unless you manually upgraded. Now they are allowing themes to access images that are not stored in the theme folder, so we added code to allow you to put your images outside the theme folder to survive automatic upgrades. Since the automatic upgrades are easier, that is what I now recommend…once you have moved your images to the external folder.

Thanks Juggledad, I suspected that was the reasoning, but wanted to make sure it wasn't something else that I wasn't understanding.

once you upgrade go to the following theme options and hit the SAVE button
Style & edit HEADER AREA
Style & edit CENTER COLUMN
Style & edit FOOTER