1)

Not only is the language in the Supplemental opaque, attempts to get more information from a defense committee staffer led nowhere.

Q)

,(but also) attempts to get more information from a defense committee staffer led nowhere.

이처럼 (but also)가 생략된 구조가 맞나요~?

2)

It shows hard work and risk-taking isn't all it's cracked up to be.

해석: 열심히 일하고 위험을 감수한다는 것이 그리 만만치는 않다.

Q)

해서과 지문의 구조 매칭이 안됩니다 ㅜ 

3)

When I began operations, therefore, I was literally without a shilling in the worlds, but i Had a spotless character, enjoyed good credit, and possessed a thorough knowledge of my business; advantages which I easily persuaded myself would enable me to succeed without the actual possession of capital.

Q)

advantages which I easily persuaded myself would enable me to succeed without the actual possession of capital.

이 지문에서 which 가 어떤 문법적 구조로 자리잡고 있는건가요~??

관계대명사도 아니도,, 의문대명사 인듯하면서도 잘 파악이 안됩니다..

4)

He was in dept after his previous business went bankrupt.

Q)

in dept  이 지문에서 어떻게 해석해야 되는 건가요??