How am I deep learning English?

Look at this sentence from Autobiography of Andrew Carnegie:
"Soon after this Mr. John Hay, a fellow-Scotch manufacturer of bobbins in Allegheny City, needed boy, and asked whether I would not go into his service."
The parts of this sentence which I have been trying to compere with the Croatian language, how would we say that in Croatian:
1) "...whether I would not go into his service"
In Croatian:
...ne bi li ja prešao u njegovu firmu
Why the author says "whether I would not go into his service"?
Why does the author not say "whether I would (not) go into his service?
There is the difference between that two. We in the Croatian language also say:
ne bi li ti prešao u moju firmu
and
da li bi ti prešao u moju firmu
The difference is this:
ne bi li ti prešao u moju firmu = I only ask you and ask myself of some idea, for both of us thinking about.
da li bi ti prešao u moju firmu = That's my final decision and I ask you explicitly and I expect yes or no.
2) .. go ...
We never in the Croatian would say "go in his service" but "come" or "cross" or "work"
And here is how we are like a stranger when we a sentence in the Croatian translate to the English. Because of that my professor A. J. Hoge is right when say: discard all school's textbooks and listen, listen and listen, and after a lot of months, with more or less delay for listen, speak, speak, and speak. Before the internet, the best learning was to go live in a country of the native's, but after the internet, we do not need.
3) When I have been trying to repeat the sentence, I tend to use "in" instead "into" here "into his service" "in his service".
I have been a lot of reading, but if I do not stop and deep analyzing some interesting sentence, it is only reading but not deep learning.
This Author was living hundred years before and he personally wrote the book in his then the English language. Almost every sentence draws my attention to deep analysis that is not even close to the case of contemporary authors.

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