Where is the launcher config file stored? The reason I'm trying to find it is to see what the actual command and parameters are used to launch particular programs.

For that, right click on an application and choose 'edit application' to view the info. Or use Kmenuedit - right click on the launcher icon and select 'edit applications' or search for it in the launcher.

This info is not stored in the launcher itself, but in an application's .desktop file.

These are normally stored in /usr/share/applications, and any edits made using Kmenuedit will be stored in ~/.local/share/applications

Thanks! That did it for me.