I read anything I find on dueling...
It was a fascinating part of our history. I read anything I can find on the subject. The best book I have read is Gentlemen, Swords, and Pistols.
The number of paces was a matter to be decided. Some duels were fought at such short range that the pistols almost overlapped.
This required two highly pissed opponents and didn't usually allow for a friendly drink afterward.
Still, more often than not, honor was satisfied by firing the pistols into the air and shaking hands.