I guess you have discovered that there is the Search content part
http://www.phpwcms-docu.de/index.php?searchcp
However, its functionality leaves much to wish for. At present you
cannot limit the search to only certain sections of your site, and the order in which results are returned seems to follow no useful rule. It really is very basic. The only improvement to this is a mod that highlights the search term in the results if it happens to be in the portion of text that is displayed
http://www.emediafabrik.de/index.php?de_pro_mod_somp (The instructions after download are in English).
Of course one of your criterias you could have sorted if you set up categories for your media releases (e.g. new category each month).
Otherwise I would also only know of the keyword field and the {RELATED} tag that you suggested unless someone else has got a good suggestion. Best would be of course to programme something yourself that fits exactly your needs, or you might be able to find some external scribt.
