Oh hmm, the gift cards thing -- are the gift cards no-overhead? Like, can you buy a $100 gift card for yourself for $100, and then use it to buy things with free shipping?
Yes, exactly! In Japan there's also no fees or sales tax on Amazon gift cards (physical ones), and you can purchase them in arbitrary amounts I think max 100,000 JPY (~$1000 USD). Amazon.com provides one-day free shipping with gift card purchases, but could have a surcharge for oversized, heavy, or international items. I'm not sure if any of this applies to digital gift cards though.