Yes, and "How do you do?"=how are you (at first meeting) Good luck

What do you do = What do you work with? What are you doing = What are you doing right now/at the moment?

When asking about someone's career or job, we usally say "What do you do for a living?" If we want to know what someone is doing (in the moment)... such as writing, watching television, painting and reading... we say "what are you doing?"

Yes, it is the same as what is your job? But I think "what do you do " is more native.

It is asking about work. It is an important question, especially for Americans, that can be asked in casual conversation without risk of giving offense.