what are the meanings of these phrases?

A "dream merchant" is someone who trades in fantasy, often in escapism. So, for example, a man or woman who produces motion pictures might be described as a dream merchant, because the motion pictures which they produce for the public allow people to escape to a world of fantasy.

A "one man industry" simply means that a single individual is responsible for a given enterprise, although there is an implication that the individual is energetic and productive. Industry means both a field of profitable production, and it means the quality of an individual of working steadily to achieve a purpose. In most contexts of which i can think, i would assume that "one man industry" means someone who works hard and is very productive, while working alone.

"All shades and varieties" (it would be awkward to use the plural shades with the singular variety) means any description of the specified quantity or quality of which one can think. So, for example, to use the expression in a graphically literal sense, one might write: "He had a flower shop, and sold all shades and varieties of flowers." In a more figurative sense, one might write: "She produced motion pictures from all genres, in all shades and varieties."

Dream merchant: a rather fanciful way of describing a poet, an author, an artist of some kind who deals in ideas.
He makes people think, perhaps inspires them to have ideas or dreams of their own.
So he is a "dream merchant" a purveyor of ideas or dreams.

Whoopsy, Set's got there before me. I relinquish the floor.

Did that help with understanding the words and phrases?

Set's definitions are good enough for the purpose.

I came across a "one-man industry". Same man met twice. Once as a kid and then when grown up. He was a chicken-sexer. The only one for miles. He spent all his days examining the private parts of day old chickens and separating them for different destinies. He was so good at it that he could get 70% right at 30 chicks a minute and nobody else could get much above 50 so minute are the significations and speed being a crucial factor.

I daresay he has gone now. No doubt the sex can be determined before the eggs have hatched or even before they are laid.

Cluck!Cluck!

Dear Mc Tag,

It did help me understand . Thank you. I have not been able to be in touch with this site for quite a while. Now, I will be needing a quite often.

Thank you once again.

Bubu

woopse!!!

I have not thanked Setanta.

Thank you very much Setanta

bubu

You are welcome. It was interesting for me to compare my answer to Setanta's.