the spacing rule was explained to me like this: draw two lines on a piece of paper, about 6inches apart. let the distance between them represent 12 feet. Now, draw another line exactly halfway, to represent you. If you move in either direction, you are within the 6ft "zone" of that receptacle, Thus the 12 ft spacing.
The 180 VA rule is only for calculations. As far as branch circuit load limitations,where there is any combination of non and continuous loads, it shall be sized at 125% of the load, or 80% of the circuit rating however you look at it. Unless you have some kind of rated assembly that has a 100% rating.
