I saw Inception tonight too. I though didn't find it hard to follow or be confused by anything. I wasn't surprised at all that the spinning top wasn't shown. Completely leaves it open to a sequel one way or the other. Did Cobb create the ultimate dream in limbo? Or is he really in reality? Is the fact that he saw his children's faces an indicator that he is in the real world, or was it a sign that he finally forgave himself over his wife's death? Oh, so many questions, eh? Good flick. Makes you question what reality is as much as the first Matrix.
As for why Cobb's totem was with him and who created it, it probably was Cobb no matter who's dream he was in. If you recall when they wanted to get out of the warehouse in the van and the guy on the roof had them pinned down, [that one guy] was using a rifle, and [the other guy] says he's thinking too small and pulls out a grenade launcher... Where'd that come from? These items must be a construct of their creation. Same with the train running through downtown. Another word about Cobb's totem, the top spins and teeters in a specific way. Someone can watch him and see he has a top, but Cobb is the only one who knows how it feels and spins. I would say that as part of his training, he never brings his totem with him in a dream, unless there is a reason, such as the one to convince Saito who he is.