UrbanGiraffe:
You've forgotten to plan for the inevitable insurgencies, urban warfare, and terrorism. :V
3. Legalize, regulate, and tax prostitution. (I wouldn't use it myself but I don't see any reason why it should be illegal, it just drives it underground)
4. Legalize, regulate, and tax marijuana. We already have alcohol and cigarette taxes, of course.
No. Just legalize and regulate. In an optimal world sales tax would be eliminated and he money made up for through increases in the income and capital gains taxes.
Perhaps. It'd be better for anyone who isn't well-off. However... When companies manufacture things outside the US, and ship them in to sell, if they've been clever they can avoid income taxes (via corporate inversions, etc). For them if there aren't any tarrifs then sales tax is the only way the government can tax those products at all. If we were to strike the sales tax then there'd be more sales here, but the government would get nothing out of any company that was set up to escape US taxation.
If anyone is thinking "what we need is some kind of offshoring tax," that's pretty much a tarrif, except tarrifs are applied on a per-product (e.g. sugar) basis, have existed for a long, long time, and are generally accepted to distort the economy. A common example: Sugar tarrifs to protect the US sugar industry from cheaper foreign sugar are why the US has soft drinks with corn syrup instead of sugar, because corn syrup is cheaper than either US sugar or foreign sugar after tarrif. (I've simplified a bit, but you can read more about tarrifs on wikipedia)
I'd expect applying a tarrif on all imports (or exports) to have significant negative effects on our economy, and probably on the global economy, since companies might nope out of selling to us entirely, other countries might enact retaliatory tarrifs, etc.