Bitcoin whale support lines up as trader says $14K 'most bearish' BTC price target

I am reading the book Mastering Bitcoins 2nd Edition by O’Reilly, and it says:

Alice buys a coffee from Bob’s Cafe for $1.50, or 0.015 Bitcoin

So Alice pays 0.015 Bitcoin, and Bob gets 0.015 Bitcoin, but there is a transaction fee, paid to the miner.

There are some questions:

1. Does Alice pay more or does Bob get less? (the fee has to come from somebody)
2. The way to calculate the fee seems to be a whole essay. Typically, what kind of percentage can the fee be, if it is a $1.5 coffee, or if somebody sends another person US$1 million dollar worth of Bitcoin, or if it is exchanging Bitcoin for US$1 million? But one person mentioned that it is voluntary (even the link above said the spender "may" include a fee, suggesting they can choose not to), but who would want to pay a fee if they don’t have to? I can understand if they send over US$1 million and the fee is $13, then they probably don’t mind and "want" to include a fee.
3. The miner gets the fee — is that the miner who originally did the mining of the coin, or is it that somehow, the fee (or transaction) gets encrypted and a new miner has to mine it. It is described as: all the miners compete to find the next new Bitcoin, but there is also Proof of Work (to get a fraction of Bitcoin), but there is no mentioning of the miner getting a transaction fee. How does it factor into the flow or procedure?

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