If you're using the US site, the backend is from WWTE, a part of Expedia. The fares, service, refunds, etc would largely be the same as if you bought on Expedia. Also, I think the booking site has an issue with showing fully-refundable fares.

Regarding the visa rule, I highly doubt you need an actual reservation. I'm fairly sure something that looks like one would work fine (like an old e-ticket receipt with the dates changed). Sometimes (okay, often) it's about having something that looks right rather than actually meaning something.