It's not exactly an "error", but it does have to do with how we pass the Shipping amount to PayPal -- or rather, how PayPal requires we ~have to~ pass that amount. If we want the Shipping amount to show up as a separate line-item during checkout (which we and most of our Merchants do want, to avoid confusing customers), PayPal requires that we have to pass the Shipping+Handling charge from our cart to PayPal's checkout as a Handling charge.
Shipping charges that come from PayPal's own cart or an eBay auction are the only ones that can be displayed as a line-item Shipping charge in a PayPal checkout. Since our cart is not PayPal's own cart system, and since PayPal provides no method for us to pass a Shipping amount as such, we can only either pass that amount as a Handling charge (where it will be so-identified during checkout), or just roll it into the overall order total (in which case the Shipping amount would not appear listed separately during checkout at all).
I am not sure about that Description line you mentioned, so I'll leave that part of the question for our Lead Developer to address.