Lets say I bought a pure relax with usd in the tori-shop, but I don't have enough qi for it. Would I still be able to wear it?
yes, everything bought with USD is no-qi, from what i know.
Alright, last question. Am I allowed to sell whatever I buy on the market?
Remember, it's only no-qi for you. If you sell it, you sell it as an ordinary item.