I've also worked out why my game save was gone -- there wasn't one. After I started my new game and began wandering around, I kept asking myself why none of it was even remotely familiar, and then I realized that I had been playing Justine, previously, and not the main game.
So far, I've only actually seen three monsters. I hear them all the time, but I tend to just keep moving around. I guess I've been lucky. Anyway, there's one prowling around now. I haven't been able to work out how long to stay hidden, but I guess it will become clear.
Keep them mowing blades sharp...