It is problematic for Collections to use the particular selling and defaults of the specifc photo. We should be able to set prices for photos in a collection, regardless of the defaults used in the gallery where the photo is kept.
For example, I may have a photo in a private family gallery with special base pricing for family members. However, that same pricing carries over to a collection if I use one of those photos. Similarly, if I set the default to allow "Download Original" in the private gallery, the photo can also be downloaded from the collection, and I can control it. This isn't good.
I hope ZF will allow greater customization within collections.