] Lizzy and Darcy nearly come to name calling in Chapter 11...

A minor quibble here: I do not think the danger here was descending into name calling so much as Darcy (and Lizzy, perhaps) realizing how acutely each has been observing the other (hatred of everybody vs. misrepresenting them). Darcy may wonder whether Lizzy has also observed her effect on him, really a danger if he intended not to pursue it. (How I wish I could know what each would have said next had the conversation continued!)

]...is it a wonder he asked her to dance at the Netherfield ball?

Actually, IMO Darcy is being entirely consistent asking Lizzy to dance at the Netherfield ball. Since his excuse for not dancing at Meryton was that he didn't know anyone nor have the slightest interest in them (which he may confirm later in more detail), Lizzy has to be considered an acquaintance, having spent several days as a fellow guest at Netherfield. Not to ask her now would be an even more pointed insult than it was before.

This also suggests to me that Darcy may indeed realize Lizzy overheard him at the Meryton Assembly (if he had not assumed from the start that she had). After slighting her in public once, it would be unpardonable to slight her again in a highly public venue (albeit at a private home) now that they are better acquainted.

On the other hand, I must wonder how widespread the knowledge of Darcy's acquaintance with Lizzy was, since many of her neighbors were surprised seeing her opposite Mr. Darcy. Perhaps the neighbors' amazement came from their lack of understanding of Mr. Darcy (and knowledge of Lizzy's unfriendly feelings about him) rather than lack of knowledge about their acquaintance.

...being allowed to stand opposite to Mr. Darcy, and reading in her neighbours' looks their equal amazement in beholding it. (Ch. 18)