If you find your soil is not acidic enough try adding pine needles into the mix. But don't go overboard, because very acidic soil makes for small potatoes. To fertilize soil before planting, use well-composted manure. Fresh manure will burn the tubers. 5-8 pounds of potato seeds should be sufficient to plant a 100 foot row.
Potatoes are perenial.
Left in the ground they will come up year after year. Nevertheless, they are usually treated as an anual, as the edible part of the plant is the root and the plant must be dug up to obtain it. Cut seed potatoes so that one or two eyes are on the surface of the potato, leaving some of the meat of the potato for initial energy for the plant. Plant with the eyes facing upward about 5 inches deep and 12-14 inches apart. Potatoes are typically planted 2 weeks or so before the last killing frost of the spring.