Differentiating how/why Japanese interrogatives? なんで、どう、どうして、どうやって
こんにちはみんなさん、

I have a really big test on Monday so any help would be appreciated.

Could someone help me find the best way to define the differences between these interrogatives? I have put the definitions I have so far for them, but some of them are so similar!
My textbook is みんなの日本語

なんで
Textbook: why/how casual
Dictionary: why, what for, how by what means

なにで
Textbook: more emphasis on how than なんで, less casual
this didn't show up in my dictionary

どう
Textbook: Nはどうですか asking about an impression
Dictionary: how, in what way, how about

どうして
Textbook: asking the reason for something
Dictionary: why, for what reason, how, in what way, for what purpose, what for

どうやって
Textbook: way or how to do something
Dictionary: how, in what way, by what means

So what is the difference between:
どうやって and どう and なんで /なにで
and
どうして and なんで

Is there a better way to define/differentiate these?

ありがとうございます、
ソフィー

Question

Differentiating how/why Japanese interrogatives? なんで、どう、どうして、どうやって
こんにちはみんなさん、

I have a really big test on Monday so any help would be appreciated.

Could someone help me find the best way to define the differences between these interrogatives? I have put the definitions I have so far for them, but some of them are so similar!
My textbook is みんなの日本語

なんで 
Textbook: why/how casual
Dictionary: why, what for, how by what means

なにで
Textbook: more emphasis on how than なんで, less casual
this didn't show up in my dictionary

どう 
Textbook: Nはどうですか asking about an impression
Dictionary: how, in what way, how about

どうして 
Textbook: asking the reason for something
Dictionary: why, for what reason, how, in what way, for what purpose, what for

どうやって 
Textbook: way or how to do something
Dictionary: how, in what way, by what means

So what is the difference between:
どうやって  and どう and なんで /なにで
and
どうして and なんで

Is there a better way to define/differentiate these?

ありがとうございます、
ソフィー

Answer

I'll try to explain roughly.

****　There are  two groups.

- group 1 「何」　（'NANI' or 'NAN', a broken sound)

「なにで」「なんで」

- group 2 「どう」
「どう」「どうして」「どうやって」

*** About the group 1.

-「何」 ＝　what
-「で」＝「にて」＝「に」＋「て」
　「に」: place, target of action, where you are, where you do to.
  「て」: indicating 'completion' in terms of aspect

then
「で」means: platform of action, where you do.

「なにで」:　with/on what? -> 【using what?】(syntactically OK, but rarely used)

「なんで」: with/on what -> (sound broken) -> 【why ?】
      
※ なんでそんなことしたの？　why did you do such a thing?

*** About the group 2

-  「どう」: how

※ 君たちはどう生きるか？
　　（how do you live your life? )

- 「どうして」≓「どうやって」 : 【how/why】
　　　して　is a polite form of 'やって'

※　どうしてそんなことするの？　why do you do such a thing?　
※ どうしたらそんなことになるの? how come it become so ?
※　どうやってこの苦境を脱するか？
　　　how (=through what) do we get out of this hardship?

- 「どうして」＝「どう」＋「して」
　　　 by doing how
         -> in what way do you reach here
         -> tell me the process
         -> 【why 】

※　どうしてそんなことするの？　why do you do such a thing?

Answer

なんで　is WHY. なんで　日本語を勉強しますか。Why do you learn Japanese.　日本へ行きたいですから。Because I want to go to Japan.
なんで　is also BY WHAT. 何で　大学へいきますか。You go to the school by What?　バスで大学へいきます。I go to the school by bus。
If you take the whole "なんで" in a phase, it means WHY
And if you separate it like two individual words,　”なん” and ”で”, it means BY WHAT (Nで　V　－　Do V by using N)。
So my teacher said that to make it more clear, younger today tend to pronounce "なにで" with the one with meaning "BY WHAT" or "HOW" (何 has two ways to read　なんーなに, depend on which word follows it.)

**********************************************
どうやって and どう and なんで /なにで
＊＊＊
どうやって : How to do ... . どう: How / やって : やります：Do
どうやって　大学へ行きましたか　How did you do to go to school?
ー＞私のうちから　Mariaさんのうちまで　あるきました。そして、Mariaさんのバイクで大学へ行きました　I walked from my house to Maria House. Then I take her motorbike to run to the school.
＊＊＊
どう:　How。 to ask about characteristic
あの人はどうですか。How is that person?
ー＞とてもハンサムです。Very handsome
＊＊＊
なんで/なにで:　By what as I said above
**********************************************
どうして and なんで 
I think they are the same. Maybe just the different about the politeness

Sorry about my bad English.