I'm not sure I'm thinking of this the same way as you.

The css popup I'm considering, using 'hover,' would involve just putting a call to the popup_search_help language file, for example, in tpl_advanced_search_default.php and CSS appropriately. This would give an instant popup on hover over the Search Help [?] link, whereas a Zen Magnific popup would always involve a page load.

My main thinking is to use popups more extensively to convey information on mobile devices. Hover seems to work in Android touch environment ok but I've still to test on IOS.