aff was started as a small archive, in response to the M rated stories being pulled at ff.net. There is no affiliation between the sites.
I have a general idea of the what's and why's overall, but someone else who's been around since the beginning on the back end of all this would be better served to outline it all for ya.
I CAN tell you from recent experience, that we're actually addressing things now that should have been addressed quite some time ago, simply due to the growth of the archive itself. It started out with something like 200 stories altogether, years ago. Of course, there's much more than that now. So, now we're in the process of making software to fit the site needs, while also shoring up, stabilizing and maintaining what's already here and in place, which we've outgrown. The current software itself simply doesn't provide the functions and capabilities we need for an archive of this size.