1. Each of us has something to do.

2. We each have something to do.
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Do we have to us 'have' in Sentence 2? How come?

3. Do you like the game?
- Yes, I like it.
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Is 'it' a personal pronoun or a demonstrative pronoun?

Sentence 2 needs "have" because the subject is "We" (a plural subject).

In #3, "it" is referring to "game.," but it's not demonstrative.
http://grammar.ccc.commnet.edu/grammar/pronouns1.htm