Could you say "Comment t'appelles tu?" or "Comment s'appelle t-il?" ?

"Comment t'appelles tu?" is an informal way of asking someone "what's your name" and "Comment s'appelle t-il?" is when you are asking someone else "what is his name?" the formal way to ask for someone's name is "Comment vous appelez-vous?". A common way of asking that same question is "comment tu t'appelles?"