As for using Bourbaki to help us in
set.mm, I would strongly advocate following the global architecture/sectioning as close as possible, barring some necessities with computer checking that I have not thought of. I am not very happy with the current sectioning of
set.mm, and a while ago, I began to tweak a bit the order of the parts and sections (not actually in
set.mm, but in a draft), and the more it went, the closer it was to Bourbaki's TOC. The first six books of Bourbaki are very unified, and there are no (or almost none?) forward references (except for the examples, famously in between stars). The TOC was well thought out by a group of top mathematicians to emphasize the unity of mathematics and to permit a systematic treatment of the fundamental structures (which, by the way, is the title of this set of the first six books). It would be hard to find a better ordering of the sections.
The biggest problem with Bourbaki is that it ignores categories (it uses the less agile "espèces de structures" instead, which was nonetheless, as FL wrote, historically significant, together with the mere fact of "thinking structurally"). Category theory was developed in the 1940's whereas Bourbaki began in the 1930's, and it would have been too much work to make the change after the global architecture of the treatise had been set. But
set.mm does not use categories either, so this is not a problem.
By the way: I started a few months ago to try and formalize the first chapter of the first book of Bourbaki (logic). Indeed, it starts at a very low level, more than most logic textbooks that I know of, and this fact was very interesting to me. While trying to adhere closer and closer to the Bourbaki treatment (the things called "assemblages", etc.), I realized that this was not very far from doing "metamath in metamath", and that one should directly aim for this. So I stopped my project, and I would be very interested in hearing from Mario (or anyone) if the "metamath in metamath" project is dormant, on its way, soon to be resurrected...
Benoit