I'm partway through the installation of an 8100NEX in my 2014 Scion IQ and I'm a bit stumped! Could anyone help me with the following answers?

 

• For the orange/white cable for the "lighting switch terminal," I have 2 options of where to go on the car: the "illumination" cable which is orange and the "Dimmer" cable which is orange/white. Any insight?
• I just want to confirm that the blue/white "System remote control" cable should go to my car's blue "Antenna Power" cable. If not there, then where should it go?
• Where is the Speed Signal Input?
• Can I mount the GPS Antenna under the dash?