You are a dream expert? Please do tell how dreams work.
I'm no expert, but I'm pretty sure there's no "limbo" I'm in danger of ending up in if I dream too hard. And I'm pretty sure if someone designs a whole video game level for me, I'm not going to perfectly visualize it in my dreams. And I don't need to die in my dream to wake up, sometimes I wake up just from realizing I'm dreaming. And I only need to get jolted once in the real world to wake up, I don't need simultaneous subconscious jolts on multiple levels of my dream. And I'm pretty sure my subconscious is not ready to manufacture dream bullets at the first sign of an intruder... and so on.
I'm not saying the movie isn't internally consistent (though I have my doubts), only that these rules have no basis in dreaming as most people experience it. So they just come off as random.