Been done to death here, I don't believe it's possible to learn all the possible questions that might come up. You may get lucky, but in the later exams you'll see it's not quite as straighforward.
You have a point, assuming the system is perfect. But (again as posted many times) a large proportion of the questions are badly worded and poorly translated and they try to catch you out more than they are a fair test of knowledge, so I've no problem using feedback to get to grips with a poor system. Besides all the actual US questions are freely and officially available, so why not here.
Getting your ATPLs doesn't make you a pilot. It's just a hurdle. Treat it as such. The important stuff comes later.