Bernhard / Levi Lieffmann (Seeligmann / Meyer) - Bernhard / Levi Lieffmann (Seeligmann / Meyer)

Hi there RVK and Michael Max Liffmann
My name is Julian Duband. I live in Melbourne Australia.
I'm seeking info about Bernhard - he was my Great, great, great, grandfather (direct relative 5 generations back)

He was the great great grandfather of my mother Helga Liffmann born 1922.
I am Helga's son.

I'm starting to investigate our family tree - actually my 12 year old twins are doing it for their Roots project at school.

I have some questions you may be able to answer:

Is Levi, Bernhard's middle name?
Is Lieffman sometimes written as Liefman?
What is the whole name change about? Was his name Bernhard Seeligman?
What is the Meyer?

I'd love to know the answers.
I'm hoping you will answer me as I'm very much fascinated and since mum passed away just last year at 99 years of age, I want to know things
that she was never able to tell me or talk about.

Kind regards
Julian Duband (Melbourne Australia)