I read this article and unfortunately don't know enough about plumbing to understand the answer. https://homeguides.sfgate.com/size-pex-pipe-home-plumbing-102381.html

What is a main line? It says to install "1/2-inch or 3/4-inch PEX for your main lines"

Do washing machines require a thicker diameter pipe?

What diameter is standard for showers and faucets?

Is the kitchen sink faucet the same as the rest?

I know complete newb questions but I'll never learn if I don't ask.