Is there a way to show lyrics, etc on the foldback monitor without showing them on the screen that the congregation see's?

This is easy to accomplish. Click on the Clear button at the upper right of EW to remove any words on a slide of the Front of House screens leaving on the background showing while it leaves the text on the Foldback screen. You can also click on the Black button to have the FoH screens to turn black leaving the Foldback screen intact. 

You can also set a specific image file as a Logo image and use that button the display that specific image while the text appears on the Foldback screen intact.