Read the label. Most dangerous one is acetaminophen/paracetamol, avoid more than 1000 mg at a time or your liver can be damaged. Sometimes it is mixed with hydrocodone so make sure you aren't taking those.
Depends on your weight and age.
Four is the safest of standard caplets of Advil.
Nah, I'm 16, weigh about 115lbs, and take 4 when I have a massive headache. I typically don't need more than 2, but 4 won't kill me.
Eh, you didn't OD. Just never take more than 4 in a 6 hour time period.
No, but I know enough to read the information on the back of the package.
too many, lol.