How can I change the wording of the "In Honor of" tab?
One option is to use the .extra.tpl method (original blog post, forum post or from the wiki) to add jQuery to the page.  To identify a potential starting point for which tpl file to use in front of .extra.tpl, right-click on your contribution page and View Source.  Then do a find (usually CRTL+F) for tpl.  The forum post suggests that a good starting point might be CRM/Contribute/Page/Tab.extra.tpl.

You would select your particular field labels and use a jQuery function like .replaceWith().