No, I don't.

I tend to go for notes chapter-by-chapter. Among other things, it takes long enough to read a chapter that I get to the point where I can remember any particular idea with ease but the flow of concepts has mostly been lost and all of the pieces have been shunted into long-term memory. If I can mostly reconstruct the chapter, great, if not, I go back and figure out what was where and why it was there. (It might be worthwhile to always go back and see what you missed / got wrong, but that would probably get close to doubling the necessary reading time.)

I do, but it's mostly because doing it helps me focus. I rarely go back to read my notes. Here's an example, for a book about SQL query tuning.

I tried doing this briefly when I was experimenting with Workflowy but I found it excruciatingly boring and couldn't keep it up; it was close to ruining reading non-fiction for me and I stopped immediately when I noticed that.

Yes, if I don't take notes on the first reading there won't be a second reading. Not much detail -- more than a page is a problem (this can be ameliorated though, see below). I make an effort to include points of particular agreement, disagreement and some projects to test the ideas (hopefully projects I actually want to do rather than mere 'toy' projects).

Now would be a good time to mention TreeSheets, which I feel solves a lot of the problems of more established note-taking methods (linear, wiki, mindmap). It can be summarized as 'infinitely nestable spreadsheet/database with infinite zoom'. I use it for anything that gets remotely complex, because of the way it allows you to fold away arbitrary levels of detail in a visually consistent way.

I'll usually:

• Use a piece of paper as a bookmark on which I take notes (noting page numbers of bits I don't understand, attempts to summarize/reorganize, interesting insights, notes while I work something out, random ideas the text gives me) - it's not rare that I end a book with two or three pages of notes stuffed into them. I'll then go over those notes and maybe enter some bits in Anki
• Directly enter stuff in Anki if it's atomic enough (it often isn't)
• Takes notes in Google docs (either if I'm near a computer at a time, or if I want to have "searchable" notes or look up related info on the internet)

Usually I'll read it in depth first, then once I know if it's worth taking notes, I'll return to it and scan through quickly for those points I know are worth grabbing.

I've fairly recently (over the past month or so) started taking notes on pretty much everything, as part of a drive to capture as much useful content in Evernote as possible. A lot of what I'm doing at the moment is probably quite wasteful, but I expect to figure out what is and isn't useful in fairly short order.

For ebooks I've been making judicious use of highlighting on the Kindle. Unfortunately the UK Kindle service isn't as feature-rich as the US counterpart, so I'm still looking into ways of parsing my clippings file into Evernote. For hardcopy books and lectures, I've taken to either writing bullet-pointed lists or mini-essays. This also seems to have the positive side-effects of forcing me to clearly elucidate on ideas I've just taken in, and stopping me ruminating on the areas in question.

For example, late last night I was reading about the concept of "burden of proof" in legal and rhetorical contexts. This is a bit of a personal bugbear, and I ended up writing several hundred words informed by what I was reading. Not only can I now reference this when necessary, but it stopped me from trying to sleep with a bunch of proactive burden-of-proof-related arguments running through my head.

I answered a similar question here.

As I read textbooks, I summarize the most important concepts (along with doing the exercises, if there are any) and write them in a notebook and then later (less than a week) enter the notes into Anki as cloze-delete flashcards. I don't have an objective measure of retention, but I believe that it has vastly improved relative to when I would simply read the book.