Explain why models might be used instead of words to communicate new ideas.

Different people learn in different ways.  Some are audible learners and some are visual learners.  Some are even kinesthetic learners who need to interact with what they are trying to absorb.  So the more different ways the material can be presented, more likely the audience will be to truly understand the new idea.

Hope that helps.

It really doesn't matter for any of the questions that you've listed.