A few questions about Shopify

1. Can I make more Shopify stores and use them all on my 1 FB ad account?

2. Do I have to pay the taxes to the US IRS if I'm not a US citizen and live abroad and if I use Payoneer card or some other card and a foreign bank account?

3. Can I advertize that I would donate some % of the profit to charity in order to make more money, and who and how is going to check it to see whether I actually do it or not (I don't plan on cheating anyone, but am interested about how that would be monitored)?

1) Yes. No problem with multiple domains.

2) Only if you're buying from Amazon and reselling through your own shopify store to RESIDENTS of states where Amazon has fulfillment centers.

3) Usually people don't check but you might want to make the badge clickable so it's more believable.