You need to pay capitol gains if you hold the coins for a year or more.
More than a year. A year or less is short-term gains (in the US).
If you spend them right after buying them it can be said you are using bitcoin as a payment network and not an investment. If spending/selling after a year try this formula.
It makes no difference, it is still a tax event. Any gains made on the coins are taxable.
Thanks for the clarification. I do not know myself. But I have heard a lawyer say that if you buy then use coins as a payment system you might not be liable.