I am developing a site that I want to hand over to a client once complete. The core page 'content' is manageable, but there are elements of content (common headings, titles etc.) that are shared across multiple pages & sections within the site, and I would like to give the client a single 'admin page' where they can set all of this information; there are about 25 bits of configurable content - all of them small strings.
You should build a theme settings page for all the "global" settings like social media url:s, phone number etc..
It could be something like this:
Here is a guide how to make a Settings page:
Or you can make a settings page with the new Customizer that comes with WordPress 3.4 so you can see your updates before you save it:
Look at this video to see what i mean: http://www.youtube.com/watch?v=vD8v6u3noPg&feature=player_embedded
And here is how you can do it: http://ottopress.com/2012/how-to-leverage-the-theme-customizer-in-your-own-themes/
That would be a perfect use of the Transients API. Just store the values in transients and you can access them easily anywhere in your theme using: