1. For C172 (or similar) you need to use the "Nose_Wheel_Steer" On/Off switch (find it in the configurator "Gear/Brakes' Tab.
When this switch is Off - the nose wheel is free, when it's in On position, you can control the wheel with Yoke Roll.
2. For analog input you can use any potentiometer from 1k to 100k.
But with higher resistance potentiometer and long wires you will get more electrical noise and input signal jerks. The less resistance (1-10k) the better.
I recommend to use any from 2 to 20 K.
It's nor related to "speed" or to "precision" which depends on the resistor quality, physical size, wire length (noise), it can be a "multi-turn" pot for example. For yoke roll the default precision is set to 200 (can be changed to max 1000).