I have a childhood friend who makes me question transgenders
Why is your friend making you question transgenders?
He is a male to female transgender.
You shouldn't be questioning a trans gendered person on what they want to be called. They live their life and they get to choose what people have the right to refer to them as.
We can't do anything about it. After all I'm a cis male so it doesn't matter at all, I can't relate.
Everyone can relate to everyone else on a basic human level. They are your friend, so you should be able to feel some empathy towards them and treat them as an equal.