GPS: Anything with a SirfIII chipset and USB is a good choice. The BU-353 is a good choice.
Optical: SLim and slot loading. Tray loading drives look stupid in the car.
Sound: You have seleceted a motorized screen, so that is 1 din. I see no reason not to be able to use the other din for a hu. Just as a side though, motorized flipout screens suck big time. You will be replacing it in the near future when it fails. Not "if", when.
Frontend: RoadRunner ftw! Cost: $0