Those who choose to smoke and die have that right. However those who smoke whose second-hand smoke kills others are murderers. Aren't they?

No, not unless you can show they intended to kill a person. The worst you could maybe make a case for is manslaughter. But still would have to take place over years.

Most people choke outside now. So if anyone is breathing that second-hand smoke it that person's fault. So is that suicide?

No that is much too strict a construction. Everything we do really affects everything else and in most cases we can never know if we have set in motion something which will result in the death of another person.  We live with someone who smokes yes we are affected but we have chosen to live with them.  We make such choices constantly. Our spouse becomes sick and chances are will make us sick too and if we die can they be prosecuted?  No nor would we expect them to be.  The Chernobyl nuclear disaster spread radiation all over the world and who knows how many people wherever died from being exposed to it.  I knew one person who was a hospital administrator and a church lady who went on a mission to help the local victims of Chernobyl and was exposed to the radiation and died oh about ten years after her return home.  Has a lot to do too with our personal abilities to throw off infection - our immune system.  I stopped smoking years ago but if I am with people who smoke now I certainly would  not inhale!