How to create a public-facing database?

Hi!  I have been working to build a contact manager for my organization in FMP, and it is coming along nicely.  I'd now like to create a way using Webdirect for the public to search a limited subset of the data.  Ideally, a Filemaker search layout would appear as a frame within a Wordpress page, or something similar. I think I have figure out the permissions for guest access and how tightly they should be drawn. The layouts and scripts are in reasonably good shape. 

Having gotten all this set, what I'm having trouble with is the basic structure.  Do I set my database to "Log in using Guest Account," which seems to complicate my staff's logging into the database?  It almost seems like WebDirect has to be used to provide either guest access, or staff access, but not both.  I didn't expect this complication.  (It appears that it wasn't an issue until passing parameters via URL was removed...)

Does PHP or XML have to be used instead?

Many thanks!

Tom