multiple "incarnations" of the same gallery

[Mike James]

I am currently using the Singapore photo gallery (http://www.sgal.org/).  On my site, I display both personal photos (family, friends, photo-blogging, etc.) and photos taken on professional assignment.   My personal photos are presented in a big gallery integrated into my personal website, and my professional assignments are presented individually at another location (on the same site).

The difference is that my personal photos are all part of a big gallery, which is integrated into the theme of my personal site, and clients get another page, with a totally different theme, to view their photos.  In the latter case, sub-galleries don't link to one another - each project is isolated from the rest of the gallery.

At the moment, I have to operate each gallery separately:
---  photos that appear both in the personal gallery and in client galleries have to be uploaded separately
---  each individual client gallery has its own codebase

What I'd like to do is combine the gallery into one project, displaying different photos and different themes depending on how a user is signed in.  The former could be easily accomplished with image/gallery permissions, but I'm unsure about the latter.  I'd like things to operate such that:

1.  images can be displayed in multiple galleries
2.  galleries can have different templates according to the group to which a user belongs
3.  users with permissions for only one gallery should go straight to that gallery when they sign in
4.  individual client galleries don't have a link to the root gallery

Does the Coppermine Gallery script support features/applications like these?  If not, can anyone speak to the relative ease of making modifications to the code?