Personally, I don't ship anything that's not over 3/4" wide with tracking per USPS requirements. I use stamps.com so I would ship something like this in an envelope without tracking. But Pirate ship doesn't allow for envelope/flats shipping, only packages, but that's just my preference, it's the reason I don't use PirateShip.
Sure thing :D You can ship anything through Stamp. com, but not so much with other shipping sites, not even Paypal shipping --most only do packages or, express or overnight envelopes which are very expensive. Listia frowns on excessive shipping costs too ;D