To get an idea of the canvas that is the human face many make-up designers will elect to take a picture of the actors face so they can see their canvas.
When your show needs elaborate make-up you want to have an idea of what it will look like on the actors before you apply it. You will need to make some renderings. Depending on how complex the make-up will be will depend on what kind of renderings you need. These renderings will be shown to the director to get their input on the make-up design and any modifications that are needed.
If your show is using heavy make-up or needs to achieve a specific look then you need to know how its going to look onstage, thus the make-up parade! In concept it's very similar to a costume parade, the Make-up Designer applies the look to the actors and presents them onstage (usually under the lights) to see how they will look. For shows that use stylized make-up this is a very important parade. Unfortunately much like the costume parade this is falling out of practice as well. Again with more plays set in modern times elaborate make-up Is falling out of use. For grand scale productions the make-up parade is truly a site to behold.