Paracetamol is toxic for the liver. Your body also becomes used to it so that you can get rebound headaches when you don't take it. It is vital that you do not take more than the recommended amounts.
Very easily. More than 20 accidental fatal overdoses per year in the uk. Take something else, because paracetomol is very toxic. A fatal dose can be as few as 8 tablets at some strengths (lower for people with poor liver function, higher for others).