1. Why would anyone want to accept a currency that doesn't ensure "profit" on tomorrows trade rates? Do you have to write terms that says "If BTC drops below blah blah- I am not willing to process your order" because this can ruin EVERYBODY, no one gives their goods for free!
It's not ideal but you could simply keep a float of BTC available for yourself, and sell them whenever anyone buys anything. Then when you receive the bitcoins from the customer, you have no need to convert them, you've already done it, and protected yourself against any price changes (including upwards ones mind) while the BTC were in transit.