How long it takes to write a book depends on its length.
Even if you only want to write science fiction, you should also read mysteries, poetry, mainstream literature, history, biography, philosophy, and science.
I'm in favor of any technology that makes my work available to the reading public at a reasonable price.
That's why editors and publishers will never be obsolete: a reader wants someone with taste and authority to point them in the direction of the good stuff, and to keep the awful stuff away from their door.
It's hard to generalize, because they're all different. When I started, I decided to take as much advantage as I could of the freedom offered by the SF field.
Working within the limitations of the shared world generally made the writing easier, because I didn't have to invent any of the characters or background, which is usually the hardest part.