What happens if they get stuck in a level?

I have rewatched this film and seem to have more questions now.

You die in a dream in a sedative state and you enter limbo. You have to die in limbo to get to the next level?

Why do the kicks need to be synchronised?

What happens if you get stuck in one level and wake up?

What happens if you get stuck in limbo and wake up? Can you just not dream or is your mind mashed?

How do they get out of the 1st level, when the kick of falling into the river didn't wake them? did the sedative wear off?

If the sedative has worn off, then the real time has passed in full, so the equivalent will have also passed in each level? Why is it so crucial to get out of the level at that time, other than limbo? Surely when they are woken in real life, the equivalent time will have passed anyway.

If the kick doesn't happen in L for 1 day, this would have ALREADY been 20 days in L2, 40 days in L2 etc. 600 days in L3 etc. Needing it to be in sync makes it worse at it would be mandatory to have to wait this long until the song kicks in. The waking on the plane with 20 mins left makes it seem like the sedative just wore off.

If the sedative has worn off, which is one way to get out of the dream without dying, why is it such a big deal to get to the next level down?

Are they woken in real life by the cabin assistant? why couldn't they just have one person wake the group? Is it because they needed the person in the deepest level to know it has worked?

Why did Fischer need to go to limbo to go into the safe? This wasn't originally planned? So what was supposed to happen? How does he break into the safe anyway? Is this his dream safe or the limbo safe?


I'm confused by this diagram http://www.inceptionending.com/wp-content/uploads/2010/08/INCEPTION-infographic-v3.5.2_dwang.jpg I thought that level 4 was limbo, which is Cobb and Mal's creation when they started on the beach. Is this another level of dream in Cobbs mind? Why is it so crucial that Ariadne has to leave this?