2009 Charger AC/Heater control question

Ok, first I know its not an A body, but rather then create a new account on a charger forum and you guys are hella smart.

SO, 2009 charger has manually knobs to control the AC and heater, yet the manual knobs connect to an electrical harness, so there is no cable linkage.

My question is, how the hell does this work?
If I turn a manual knob, and its connected to a wire, and this knob controls fan speed, how does it know what speed I am selecting?

I'm assuming here that the knob is connected to a potentiometer and that the resistance changes, and that affects the fan speed. Makes sense.
What about the temperature? or the heater vent zones?

Does the variable resistance determine how far cool air/hot air baffles are open?
Does the resistance determine what zone is used, somehow?

My reason for asking this is, I am putting an ipad into my dash, I have to relocate the big clunky manual AC/Heater controls to make room....id rather have the Ipad control the heater...

So that's what I'm getting at, If its some kinda resistance setup, perhaps something like the Arduino computer I've read a little about, could be used to talk to the heater and the ipad?

Anyway, any information would be greatly appreciated.