1. Depends on how big the lines are

2. As far as i can tell it always burns, and dont be surprised if after a while you nose fountains blood like a bad horror movie.

3. I dont know, i am very reckless and self destructive so id do them all at once =p

4. Cocain is a wretched drug and i would recommend not wasting my time on it, you may feel somewhat ok for 20 minute sor so then youll just feel like complete liquified shit so if i were you id put it in somebody's food and laugh at them when their mouth goes numb.