Re: database search module
There is a plugin that does that, I think its called DSN - you'll have to find it in the documentation as I'm not very familiar with it. It allows you to run a SQL query and output its contents I believe.
Another way is to create your own php page that resembles the same format as tiki-index.php, except rather than displaying a wiki page, you're displaying custom code.
Yet another way is to recreate a database from scratch using the trackers feature - I've done this myself for some things.
The way I've approached this problem (and I'm not sure if I'm doing it the right way - honestly haven't gotten any feedback about it from the IRC chat) is by creating a custom plugin. Custom plugins allow you to insert any PHP code into a wiki page. As a result, I've created entire custom AJAX'd applications using a single plugin - thus I feel its a kludge (but it'll work!).