OP here. I actually liked the pointers to F-Droid apps, too. I'm on LineageOS. I've used F-Droid for years but mainly for things like Adaway. Timber and notes apps look interesting, also K-9 of course.
This is sad news. Years ago we developed a Linux Journal Press imprint but it didn't really go very far. Many great authors have written for Linux Journal and I've enjoyed many excellent articles over the years.
I definitely agree. Book publishing, in my opinion, needs to shift to meet the changing needs of readers. Many tech book publishers continue to publish the way they have for the last 20+ years but the world has changed. We don't need more, poorly written and poorly edited documentation. We need better books.
That can change; it depends on the publisher's perspective and goals. Our goal is always to publish fewer better books. (I stole that line from Prentice Hall. They forgot it years ago. :)
There are undoubtedly royalties being paid as some (unknown) percentage of sales. The advance is essentially a loan against earned royalties. Publishers spread advances over numerous projects. The real money comes when a book sells well and the author earns royalties, unless that author is already a star and commands a very high advance like a former president, a sports star, movie star, and so on.