I'm pretty sure that "the pack" is a metaphor. A "pack" as in a pack of wolves. It means that all the people in the USA, including the president, are a part of the "pack", but that they are quick to point out the mistakes of someone in the pack. They are quick to target someone and say they are doing something wrong. "One" can be referring to anyone. It doesn't specifically mean him, but he is, in a way, explaining to his daughter what is happening when they criticize him and he is warning her about it by telling her that metaphor.

1. Yes, it does. He's drawing a metaphor between people and a pack of wolves. 2. Yes, it does, but more generally, it is a way of referring to a single agent (that is, a sentient, living being) without identifying gender. He was telling his daughter that people, like a pack of ravenous wolves, will jump at a moment's notice to destroy one of their own, especially if they're an easy target that attracts a lot of hatred (like the U.S. President).

Yes, the pack does refer to people, however the people are being compared to a pack of wolves. In this case, 'the pack' are his political enemies who he perceives as having the behavior of a pack of wolves. Think about how a pack (group) of wolves acts - vicious, predatory, unrelenting, and there are always many of them. In English, we call this a figure of speech or figurative language. See: http://www.englishclub.com/vocabulary/figures.htme The word 'one' refers to anyone because it is figurative. Hope this helps. Feel free to ask questions if I didn't explain it clearly enough.