Sunfish to my mind much of what is in that document has been mentioned here on pprune over the past couple of years. It's just that one tends to forget all of what one reads. Only today I was looking (unsuccessfully) for the thread started by somebody who was warning about his having paid for a B737 rating, but months later was still not close to getting paid due to training delays. Still only an allegation at one level, but you can actually meet these people if you want. (By which I mean that I don't doubt that most, maybe all, of the stuff in the document can be demonstrated to be true).
As for your questions, cabin crew get a really bad deal/treatment from time to time (their overall lot is probably worse than that for the majority of pilots). With Engineers I know there is a lot of unhappiness, but I cannot personally comment with any accuracy on their situation. It is hard enough keeping up with the scams in your own little patch.