Basically... the whole movie was, from scene one, about the team conning Cobb into retirement, because they had become aware that his subconscious was jeopardizing their work -- and potentially their lives. He simply couldn't be trusted to keep working, but they knew he would never stop until he was reunited with his kids -- something that was all but impossible, as he couldn't enter the States and - from the sounds of the unhappy grandmother on the phone - she blamed Cobb for Mal(her daughter)'s death, and wasn't letting them leave the States, either. So... Miles(Michael Caine) and the team (including Saito and Ariadne) created an alternative answer.
From the very beginning, it was set up to ultimately retire Cobb into a dream that brought him peace, and one he could believe was real, be it real or not. The whole story with Saito vs. Fischer was simply a setup that required Cobb to return to his limbo to confront his guilt over the death of his wife, because he would never believe any reality in which she was still haunting him(making her memory his totem?).
The only force that could commit him to face his wife was the chance of seeing his kids again, so the whole idea was to pit the two realities against each other, and gamble that he'd sacrifice the right one in favor of the other.
The whole plan kicked into gear by making him go to Mombasa, where he met with Eames and was then conveniently chased right into the car of Saito, who was in Mombasa to "protect his investment"... pretty nifty timing, eh? Eames shows up, and just so happens to know a guy who makes experimental elixirs(Yusuf)... oh, and also just happens to have his own dream farm in his basement, heh. Once there, Cobb tries out the elixir, sees brief flashes of his wife and then wakes up, flustered. Cut to him washing his face in a sink, and then goes to spin the top to verify reality -- only the top falls off of the counter, onto the floor, and before he can pick it up, he's distracted.
Reality was never confirmed from this point forward throughout the entire movie.
He was unknowingly corralled to Mombasa to be sent to the dream farm by his very own team, where he could live in the dream of his/their choosing indefinitely(I mean, sure, we were told that they only dream for about 40 hours at a time, but who's to say that wasn't a lie, and that it wasn't just a retirement home for thieves?). Opposition(the Mombasa chase, shrugged off as Cobol agents) was even staged to make it realistic to Cobb, because - just as it played out with Fischer - Cobb had to believe he was in control the whole time. It had to be his choices that got him there for him to really believe it.
So... from there, the dream within a dream within a dream was all an elaborate setup to get Cobb to confront himself. I'm also assuming that Ariadne wasn't the architect, but was placed there by his Dad and the team to be his guide -- the true architect being Lucas Haas' character, the original team's architect that was tied up and dragged away at the beginning(as Cobb said himself, it's not a good idea to bring the architect inside, so he was conveniently removed from the picture to work behind the scenes).
Once he entered limbo, confronted the memory of his wife, saved Saito and returned home... that was all still a dream, but one he could finally believe wholeheartedly; one he had achieved.
His friends, his dad... everyone he knew realized that he would never stop trying to get back home - something he could never do in real life - so they created this as his retirement gift; a reality where he could come to terms with his past and live in peace with the future he always wanted.
Did the top fall over? Probably. I'm assuming that the totems have no special powers; they only reflect the owner's subconscious belief. If the owner truly believe he or she is in reality - body, mind and soul - the totem will reflect that accordingly... whether it's true or not. What might be more telling is... he walked away from it completely. It didn't really matter anymore.
And the theater was one of the nicest I've been to. They had a little gift shop at the front with books about auteur filmmakers.
t: Thank God I have a real IMAX. A gift shop? That sounds pretty cool actually. I love big theaters. To me, it's the real experience. 
I just need a job.
