In a typical Optimus setup, all screens are connected to the Intel card. On linux, due to Nvidia's lack of support, the Nvidia card is always running, costing you battery life. And you can't even use it with all apps (the bumblebee hack doesn't really work with every app). Also due to that lack of support, you can't install the Nvidia driver manually, you must use the bumblebee script.
As for why Xorg loaded fbdev instead of intel, your chip is very new, in fact it's surprising it even runs with a 3.0 kernel.
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In short, for using the Nv card, especially on battery, you don't really have a choice other than Windows. Linux distros will run on the Intel card, with the Nvidia card still using battery on the background.
With bumblebee you may be able to run some apps on the Nv card while still outputting to the Intel card. But it's a hack, in the bad sense.