I can offer up a few thoughts on your questions.
I've not heard of any upgrades to get higher temps out of the AQ.
I came from the Bradley side as well. Because of the Bradley's poor insulation, I built a PID controller to stabilize its temp. Because the controller was so precise, it was easy to zero in on the exact temp I wanted. When I got my AQ, I expected the same performance. It wasn't as precise, but my experience has been that it just doesn't matter. A 10-20 degree swing up or down really doesn't impact anything that I cook. Also, as my AQ has gotten more miles on it, the temp is much more stable and within 1-2 degrees of what I have it set at.
I like a lot of smoke flavor, and I have trouble getting as much as I like. I have filled the box up with chunks, but it doesn't seem to add much more flavor then if I just use 2 pieces. I do know that when the initial heavy visible smoke subsides, there is a more clear smoke that follows, and that is really the smoke that many prefer.
Enjoy your AmeriQue, it's a fine unit.
Matt