Replying to @gaelicmichael's post:
Those are great questions. I particularly like #6 and #8 as a way to help refine the define. I agree with Willy Lee that one way to help focus is to get at the difference between a collection, a Collection, a collection with narrative, and a typical web site. I've found that people who do not have a background in building collections don't usually distinguish between collection=a bunch of stuff I want to organize and display, and Collection=a curated group of objects chosen according to specific criteria. Neither do they distinguish between collections and exhibits. Showing them a searchable/browsable database of objects (eg dSpace), then showing a narrated exhibit (with the objects still in a searchable database behind the exhibit, eg Omeka) goes a long way to clearing that confusion up. (And then too often you find out what they really want is a customized web site with all kinds of bells and whistles. *sigh*)
With question #6 you will be able to find out if they want to do things 'above and beyond' that will require additional apps, all of which should play nicely with your core application, so that helps determine what you need as well.
Thanks for posting the questions--I'm going to use the pedagogical ones to help frame a course project we are designing right now!