Has there been any sort of wiki or faq set up to help new merchants establish BTC rates for the products they are offering? I was thinking prices need to be at a slight premium to cash to offset the risk of accepting BTC.
Bitcoin payments are non-repudiable (cannot be revoked nor reversed). So there isn't risk that a payment received in bitcoins would get a chargeback or won't be settled.
Is the risk you are referring to the exchange rate risk? If so, then to protect against that the merchant simply executes a hedge to match each payment. i.e., Payment accepted for 2.0 BTC, a 2.0 sell on the exchange occurs immediately.
That approach then could allow prices displayed to be dynamic and competitive with cash. This approach is described here:
At some point consumers will expect that their purchases using bitcoins will be priced equal-to or possibly at a discount even compared to the equivalent cash price, but until that point in time is reached most merchants are today able to tack on a premium.
Because the benefits bitcoin offers to a merchant are significant though, expect them to wield the ability to pay using bitcoin as a competitive advantage. Thus any price premium obtainable today should be considered just a temporary condition.