Who are you and what have you done with Sidious?! She's been a mole in the BA for probably a century. Maybe two. She's compiled a list of roughly 200 Black Sisters when they take pains via cells to make sure no more than three of them are known even to each other. No, Verin's not unobservant at all, she just takes full advantage of the common belief that Browns are unobservant. In fact, I get the impression most of the Browns with great success outside their Ajah do this, but Verin admits it at one point in TGS. Mat acts like she'll probably outfox him even when he figures out all that, and when have you ever thought of Mat as unobservant? Verin thinks he's off his nut because she is observant, and because she's not to privy to all the information we are.

Just because you're paranoid doesn't mean they're not all out to get you, and Rand's under tremendous stress. Whom does Tam fault for his brush with death, Rand, or the people around him, those even of his allies trying to use and manipulate him? I think Rands epiphany is just that, one Jordan's been setting up for some time. Laughter and tears, he's forgotten he's a man, if he's too hard he'll shatter, etc. etc. No, I think the epilogue is one of the Great Moments the series has built up to, a Grand Theme Jordan's tried to convey. Without it, as I said above, I don't think Rand would have the will to fight Tarmon Gaidon. Easier for him to let the DO win and destroy the world, which solves his problem, and doesn't cost him a thing if the only thing he has to look forward to is slow agonizing death in the near future. The DO gave him something to oppose, but what he desperately needed was something to fight for. Now he finally has it.