Some problems I met reading
I start reading a book named 《Word Power Made Easy》recently, and I have some problems in comprehending it.

①What does "What’s in it for me?" mean?

②This is a tough world, pal, dog eat dog and all that, and I, for one, am not going to be left behind.

Does "all that" means"all the things like that"?
And what does "for one" mean in the sentence above?

③Probing, futile questions like “What do other people think of me?”, “How do I look?”, and“Maybe I shouldn't have said that?” are your constant nagging companions, for you…

What is the usage of "Probing" here? I mean I've looked it up in the dictionary but still have no idea what does it mean.

④Indeed, you are quite normal-in the sense that your personality is like that of most people.

What is the usage of "in the sense that"?

Thanks

Question

Some problems I met reading 
I start reading a book named 《Word Power Made Easy》recently, and I have some problems in comprehending it.

①What does "What’s in it for me?" mean?

②This is a tough world, pal, dog eat dog and all that, and I, for one, am not going to be left behind.
   
    Does "all that" means"all the things like that"?
    And what does "for one" mean in the sentence above?

③Probing, futile questions like “What do other people think of me?”, “How do I look?”, and“Maybe I shouldn't  have said that?” are your constant nagging companions, for you…

What is the usage of "Probing" here? I mean I've looked it up in the dictionary but still have no idea what does it mean.

④Indeed, you are quite normal-in the sense that your personality is like that of most people.

What is the usage of "in the sense that"?

Thanks

Answer

1.  When a person asks this question they want to know "what benefit they will receive".
2. Yes, it means all the things like that.  "For one" means "I" out of all the people in the scenario: one out of many.
3. Probing in this sentence means to be detailed, trying to get the details of something.  So, "probing, futile questions" are simply detailed useless questions.
4. In this sentence "in the sense that" means "in this way".  They are just trying to be more specific in what way that person is normal.

Answer

1. "What's in it for me?" means 'what do you have to offer me?', or 'how do i benefit from this situation?'

2. Yes, that is basically what 'all that' means.
'I for one' is a saying that means that the person speaking is asserting their thoughts as their own, that they understand their idea isn't necessarily a popular idea, or an assertion that their idea is valid, even if other people don't think so.

3. A probing question is intended to make the person answering think deeply about the issue. Usually a question that someone expects a big answer for. The word 'probing' itself means to physically explore something, so when you ask a probing question you are asking a question that needs to be scrutinized.

4. When someone says, "In the sense that...", they are narrowing down the meaning of 'normal'. You could also say, "Indeed, you are quite normal - meaning that your personality is like that of most people". It is hard to explain what this means! Wow, I didn't think it would be.