A tax credit can reduce or eliminate your federal tax obligation. One such credit is the unified tax credit, so named because federal gift and estate taxes are integrated into one unified tax system. The extent of the benefit provided by the unified tax credit depends on the tax year in which you intend to use the credit.
No, alcohol is considered a different class of chemicals than carbohydrates, even though alcohol can be derived from carbohydrates.
That being said, sugar alcohols are confusing. Sugar alcohols have nothing to do with the type of alcohol in beer, wine or spirits, and they aren't sugars either. A sugar alcohol, such as sorbitol or xylitol, is an incompletely absorbed carbohydrate. Since they are incompletely absorbed, you get only some of the calories, and your blood sugar goes up less than if you had had the same amount of sweetness with regular sugar. A rough but reasonable rule of thumb is to count about half the grams of sugar alcohol as sugar, for the purposes of counting sugar grams.