1. yes 2. very small difference 3. How do you know it doesn't work in dual channel? Is this mentioned in the board specs? The performance difference is only 5-7%, so you decide.
+1, and you need OC the RAM for the 1066MHz.
The motherboard doesn't boot when I have the 2 ram sticks next to each other. It only boots when the ram sticks are in slot 1 and 3, and CPU-Z tells me that they are running single-channel when they in this configuration.