Answer to Question 1
Clear ice forming on a coil indicates an efficient process. As ice forms, small pockets of air in the ice will cause it to have a milky color. These frozen bubbles act as small insulators and reduce the freezing efficiency.
Answer to Question 2
If the wiring is not large enough to carry the current it may overheat and cause a fire. It may also become hot enough to melt the insulation allowing the wire to come in contact with part of the equipment case that could cause an electrical shock to anyone touching the charged metal.