Re: Resolution independance and dual monitor setup possible?
This is a "feature" of X and it can't be disabled. In case of the type of twinview you are using X thinks it has lets say a desktop of 2 * 1024x768 = 2048x768. Although you might only want 800x600 of the second screen. The rest of the screen becomes "virtual" (you nee need to scroll to reach it).
Assuming you use that "1024x768, 800x600" you can access the unused space by using "1024x768, 800x600@1024x768" but this is I think not what you want.
The only way to get two different resolutions on both screens is to use the "seperate X desktop" approach as described in appendix R of the driver readme. Then both screens will be seperate but you can't move screens over (can be done if you enable xinerama but then the virtual problem is back again too). Note that when using seperate desktops the desktops are really seperate so you need to load gnome or kde on it.