Everything is good for something

Hi,

Could any native speaker tell me intrinsic difference among these sentences?

Thank you for your assistance in advance.

1. Everything is good for something. = (my version) It shows everything which is as a help to something. In this sentence, 'something' must experience an effect from everything.

1-1. It was tough for me to leave here. = (my version) In this sentence, the real spokensman is 'me' . In this sentence, 'me' is the real subjec in me a judgment about the quality of 'me to leave here' is made.

2. What is the word for dog in French? = (my version) What is the word which stands for dog in French? That word must has an ability to stand for dog in French.

2-1. Climbing that mountain was a wonderful experience for us all. = (my version) As far as we are concerned, climbing that mountain was a wonderful experience.

We can find 1 and 1-1, or 2 and 2-1 are opposed to each other in the logic meaning of [for].

Please right me about that idea.

Thank you in advance.