1,2 For both of these the use of commas help define the sentence structure. In 1 the part "if analyzed in detail" should have a comma before and after itself. See if it makes sense to you if you pretend that part was not present. For 2, if the word "has" did not have a comma after it, it would not make any sense. So try reading the sentence without the phrase "like the story itself". Many time, phrases with commas around them are simply additional details or clarifying information.

3. The sentence includes the word "you've", which is the same as "you have". Therefore, to keep the sentence tense the same (since in both parts of the sentence you are talking about the same concept [things won]), you need to use "have".

4. "since when" is a way of saying "at what time something started". So the sentence is saying that a person is asking 'when did the school begin being used as a call center?'