Re: He is to be my friend
That would be an odd one. It sounds like someone has already determined that that person will be your friend, but how could he know?
You could, I suppose, use that if you went to a fortune-teller.
You could also use it if you point to a particular lobster in a tank and say "He is to be my dinner!" (You've chosen him to eat.)
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.