Probably a little bit more, there are lots of laws, regulations, taxes and fees to think about...
Yup. In the U.S., some states require sales tax to be charged when buying locally, for instance.
BTC -> Gold Bars -> USD
I'd acquire the USD buy simply walking to one of my local exchanges. How much more expensive do you think this would be than simply doing a bank transfer over at MtGox?
Gold bullion coins trade quite close to the world gold price, but you will still pay a premium of perhaps 4% when you buy in quantity, and usually 8% when you buy smaller amounts. You should expect to suffer a similar 4-8% discount when you sell gold bullion coins back to the dealers too.
In question is how much premium you pay to acquire the bullion. 4% to 8% seems pretty low even.