Meaning of ‘after having purged by stool into it’

The passage below is from A History of the Index by Dennis Duncan.

King decides that the best way to satirize the journal is simply to quote from it: the inherent ridiculousness will be evident. He claims that Sloane’s shortcomings are ‘so Notorious from every line he has published, that his own Words will be the best Proof of what I say, and I have been so carefull in producing them, that I defie him to shew he is once Misrepresented’. But in the index these selective quotations are summed up in a phrase, a mocking synopsis that pricks the pomposity of the original by puckishly shining a light on its latent preposterousness. It is a method which King has developed from A Journey to London, and the index to The Transactioneer is a wonder of intentional silliness. Here, for example, is a passage on the effects of the opium poppy, quoted verbatim from an article published in the Philosophical Transactions a couple of years before. The author reports on a Cornish apothecary, Charles Worth, who has ‘caus[ed] a Pye to be made of the said Poppy’:

eating of the said Poppy Pye, whilst hot, [he] was presently taken with such a kind of a Dilirium, as made him fancy that most that he saw was Gold, and calling for a Chamber-pot, being a White Earthen one, after having purged by stool into it; he broke it into pieces, and bid the by-standers to save them, for they were all Gold … But these were not all the Effects of Papaver Corniculatum [yellow horned poppy]. For, The Man and Maid Servants, having also eat of the same Pye, strip’d themselves quite naked, so danced one against another a long time … The Mistriss, who was gone to Market, coming home, and saying how now? What is here to do? The Maid turned her brich against her, and purging stoutly, said there Mistriss, is Gold for you.

I enjoyed reading this passage, but I also have a few questions about it.

First, ‘is a wonder of intentional silliness’. According to my search ‘a wonder of’ does a role of emphasis meaning wonderous as in ‘That is a wonder of strength’ not in ‘Niagara is indeed a wonder of the world’. (Am I right?)

Last and difficult, ‘having purged by stool into it’.

Here, ‘stool’ seems to mean ‘fecal matter’. (Am I right?)

Even if I am right I don’t know why there is ‘by’ before ‘stool’. My english sense says ‘by’ is awkward in this position. But I don’t know how can I write it right.

(Since it was written by medieval style, I don’t dare to ask you to tell me the whole history of philology. I just want to get your approval to the meaning of stool and the awkwardness of ‘by stool’.)

And the last of last, what does the underlined it stand for? It seems to represent the chamber-pot. (Am I right?) And since it was broken into pieces, it becomes ‘them’ and ‘they’ that the delirious man tried to deliver to by-standers. (Am I right?)

Thanks in advance.