1: Poision ivy just plain sucks. it, hurts, itches and causes the area in which it is on to swell.
2: once the oil is washed off the skin, the liquid on the rash can not infect the rest of your body.
3: nothing seems to help for long
4: see number 2 but scratching does not spread poison ivy but does damage the skin.
5: You can get it from a dead plant.
6: see number 1.