The last one you mentioned is possible to bowl. A few years back I worked on it for about a few months before I could bowl it well. However, it is ridiculously difficult and inefficient. Even the most uneducated slogger can pick it from the hand and it requires a very slight straightening of the elbow to bowl it fast and flat. Thus, it looks exactly like an off break. It has the same position as an off spinner's top spin delivery, except the fingers apply a weak backspin to the ball, almost just as much as a fast bowler's stock ball.
I bowled it a few times in matches for the sole reason that you can get quite a bit of swing with it due to the fact that the seam is upright. It was not useful for any other purpose. The flipper is a better variation, and even that was mostly used for intimidatory purposes by Warne, not so much for picking up wickets all the time.
So people say, but no-one has ever produced video footage - when they have, it turned out they were bowling a slider by accident. That's what I think happened to Philpott.