Hmm, it's been so long since I read ATB, I shall have to add the amusing introduction to the list of reasons to dig out my office!
On the whole, though, I enjoy the speculation over these vague and sometimes contradictory questions that seem to have no hard-and-fast answers (and for the record, my personal feeling about balrogs is that they do have literal as well as metaphorical wings -- it's hard to spread a metaphor to the walls -- but that they are there only for show, an aspect of a chosen Maia form intended to strike fear into the hearts of foes by making them appear bigger and more powerful and thus more terrifying, thus also making them the largest "penguins" of ME, flightless). Everyone will come up with answers that make sense to them, if they feel they need an answer, and if they don't, all well and good, too. "Canon," I think, doesn't need an absolute answer for everything. Facts may provide proof, but they so seldom fire the imagination, IMHO. Arguments, oh, yes. I cannot help but think of friends I used to have who were armchair historians, sharing their love of history -- until they hit upon a subject for which one's preferred favorite source conflicted with the other's preferred source. More than just flames always ensued, and in the end, nothing was resolved because they couldn't even agree to disagree. Much better, I think, to endlessly speculate, and agree that there is no one answer, because the only source who could have provided one is no longer with us, and did not leave that desired answer behind.