How do you say "Good Morning" in Spanish? ~ Cómo se dice "Good Morning" en Español?

They are all correct / Todas son correctas 

Which greeting would you use in the afternoon? ~ Qué saludo usarías por la tarde?

How do you say "Good Evening" in Spanish? ~ Cómo se dice "Good Evening " en Español?

 Which is the most formal way to say "goodbye" in Spanish? ~ Cuál es la manera más formal para despedirse en español?

In Spanish, it's very common to greet by asking, "How are you?", although don't expect a great conversation.