Electronic – Should ferrite beads be closer to the stepper motor or to the motor driver

Interference is unlikely to disrupt a signal powerful enough to drive a stepper, but the resistance of normal ribbon cable is a likely problem. On the other hand, interference from the motor cable could disrupt other circuitry nearby, so some shielding might be called for.

Two experiments:
(1) run both steppers off short cables; they will probably work fine. (If not, give the "far" one its own driver amplifier)

(2) Run thick wire (cross section at least 1mm^2) to the far stepper motor to reduce the resistance in series with the motor. There's not a lot you can do about the extra inductance of the longer cable, but at low speed it's not likely to be such an important factor. This should give reliable operation up to a certain speed; but you may have to reduce the rate on this axis a little compared with the other axes.

1. It probably won't make a difference. If you google "wire resistance" you can find tables that deal with your setup. Basically, 18ga wire has a resistance of 6 ohms / 1000 ft. 6 feet will be just about .04 ohms. Your motors are 1 A. So for B) the voltage drop to the first motor will be .08 volts, and to the second, .16 volts. For A) the numbers are .16 volts and .24 volts. If you're using an H-bridge with current control (rather than switching 5 volts), this will make no difference at all. If you're switching 5 volts, it's still a small effect.

2. Sure, go ahead. It won't matter, but it might make you feel better about the possibility of pickup. Ground the bare wire at the controller end and not at the motor.