Cold cathode is a cathode, an electrode that emits electrons, which is not electrically heated by an element. Cold cathodes are used in gas discharge lamps such as neon lamps and discharge tubes.

No, there are some cold cathode vacuum tubes. These do not light.

Yes and No, some people may be affected by it some people won't this all varies on your body's natural resistance against electricity. If you exercise caution when using cold cathode inverters(or anything that involves high voltage or high current) you will be fine.

gas filled cold cathode glow discharge tubes.

has common cathode