Does the fantext play a role in fanfiction that is somehow different than the equivalent (meta)texts in other social endeavors?

Yes, I'd argue it does. Fanfic is as dependent on that cultural context as the next original fic, but only fanfic has a ready made authorship familiar with what amounts to loads of shared knowledge and texts...now, I'm assuming community membership (the virgin thing again :-), but there usually are a number of stories community members share (even if they haven't read a given story, they'll have seen discussion), there's discussions that most readers and writers share and are aware of...so, yes, i believe it is another level here that may be similar to that of other tightly knit groups (hmmm..thinking bloomsbury circle or something) but that is differnt in degree if not in kind from reading and writing within the public at large (i.e., even tiue-in novels give info dump and character descriptions...even there where you'd expect source text awareness that can't be presumed!!!!)

for a more detailed explanation, see my recent conference presentation, where i spend a very long time making this argument :D