This is not exactly a job for Word.
If your users have Word 2013 or later you can have text following heading styles collapse and expand. Your users would have to know how to do this. You could have the beginning of your FAQ explain this.
Here are some other advantages of using heading styles.
Why use Microsoft Word’s built-in heading styles? by Shauna Kelly
Look also into the Navigation Pane which is accessible in Word 2010 and later.
You might do more with macros and/or userforms, but your users would have to permit them to run. This would not necessarily be better, anyway.
Here is such a heading collapsed in a Word 2013 screen:
... and expanded:
The little triangles (in the circles) do not show up in a printed version. The triangle to collapse a section only shows up on a mouse pointer hover. The one to expand a section is visible on screen but not in the printed version. The printed version will be collapsed if the on-screen version is.
You would want this to be a
template rather than a document so that use would be less likely to alter it.