4) Yeah, I think it was an "audition" set up by Saito to see if he'd be able to tell whether he was dreaming or not, though I was confused by that at the time. I'm not sure who the guy chasing him was, when he met the forger. That was a bit confusing for me.
8) I was, a bit. It looked a bit like a corporate city or something. Like a really boring, desolate downtown area, with a couple of old country house remnants from another time period. I mean, you got 50 years! Do something cooler!
11) It did, to me. I thought the movie did a good job at making it seem like the alternate realities were ultimately unsatisfying. I wanted him to be able to get out of his dream existences and really get to have a life with his kids. To reclaim his hold on what's real and what's not, and maybe to try to get rid of the guilt he's carried around. I did like that they didn't really let you know for sure. I could have sworn the top was slowing down, though...
I wondered why Cobb couldn't just kill himself and Mal to get out of limbo the first time, too, for the greater good. But then maybe he felt like it would do irreparable damage to their relationship to force his wife out of the world she loved. And then ironically, it did, anyway.