I appreciate you sharing this! I just published my first book (nothing about programming, its about how the nation of Estonia modernized post re-independence and became a tech/e-gov hub in a single generation) and I can sympathize with a lot of this. My experience was a bit different -- I also knew the advance was going to be nothing and had a day job so I said I didn't need one (which was a relief for them as I was with a smaller publisher) and instead asked for more books to give away and some other contract terms. It took many months of negotiating to finalize the agreement and then they wanted the manuscript in ~7 months from contract signing. I guess they also assumed that I'd miss at least one deadline but instead I took a bunch of time off to get it done. I think the most important lesson for me is that book publishing, unless you're focused on trying to be the top 1% (maybe even .1%) in a popular category, is not going to be very lucrative, especially with a publisher that takes a major cut. It's easier than ever to go direct, in my case because I had a niche book and I wasn't doing it for money, I valued the prestige (or perceived prestige anyways) of having a book with a name brand publisher as I thought it'd be more helpful for my career in other ways, and candidly was mostly a passion project that I didn't feel strongly about monetizing!

If any folks want to talk about nonfiction publishing, I'm always happy to chat as many people were incredibly generous with their time for me and I'd like to try to pay it forward.