1) Applying discount codes store-wide - Currently I have to add a discount code to every single product individually which can take absolutely ages. A simple 'apply to all products button' would be really helpful
2) A shopping cart - I think it would make more sense for customers to be able to add multiple items from the storefront to basket. We see one-time customers frequently and feel we'd generate more revenue if they purchased from across the storefront in one go!
3) Ability to change between currencies - I'm UK-based, but the payouts section, which is very helpful for bookkeeping and accounting, is purely in dollars, with no option to switch/convert to pounds. Would be a nice feature.