1. The characteristics of a dangerous screen name would probably say something prvertic or something that deals with violence. It could also have things like racsim and an extrem hate towards something. Also if you use your whole name. Or if you put your phone number in it.
2. The characteristics of a SAFE screen name would be like using only your first name, or even your nickname. Also not using personal info. For example instead of putting my full name, mine would be something like Natasha or my nickname Tatasha.
3. Meeting someone online is super dangerous. It could be some lonley 40 year old man talking to you, saying he is a 15 year girl.
4. You shouldn't reply and block the person.