This passage is an example of indirect characterization through dialogue. I the conversation there is not much content to characterize Pat and Terrence but the audience can get to understand some things about each one's personality. The audience can infer that Terrence is more direct and extrovert while Pat is shy and introvert but there are not as many clues to be sure about this inferences.
A. Short answer
http://www.dictionary.com/browse/objective-test
Both are equally as important. It’s great to learn from your own mistakes because you suffer the consequence or thrive in the reward. But same for learning from others. If you are surrounded by people who are a bad influence, they may suffer the consequences of their actions and you will know not to make the same mistake they did. If you surround yourself with a good group of people, they may be rewarded for something they did or an achievement they reached, so it may encourage you to do better or be a better person like your friends.
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