I haven't used it since 5.0, and only used Quark briefly. But seven years later there are still things I wish I could do.
One thing for her/you to consider is the difference between a DTP app and a word processing app. To something like Word or WordPerfect, each file is a single document. You may have graphics and text boxes, but it's all part of the same doc. If you add text to a paragraph it reflows everything after.
With a real DTP app every item is a separate document. You can delete/resize/move any item without affecting any other item, and you can have one document span multiple text areas. The "document" you're working with is a set of pages, and you place items on those pages.
If you've never worked with one yourself, supporting her will require using it some yourself. Your assumptions about how a word processor work won't be relevant.