According to Texas AgriLife Extension, "Canes can be pruned to varying lengths, and when they consist of only one to four buds, they are referred to as spurs, or often, fruiting spurs. Grapevine spurs should not be confused with true spurs produced by apple, cherry, and other fruit trees, which are the natural fruit-bearing structures of these trees. On grapevines, spurs are created by short-pruning of canes. Training systems that use cane-pruning also use spurs for the purpose of growing shoots to be trained for fruiting canes in the following season. These spurs are known as renewal spurs, indicating their role in replacing the arms."

http://articles.extension.org/pages/3...

For more information on Spur Pruning of Grapevines
https://www.fassadengruen.de/en/grape...

We are not sure about pruning the new growth but usually the non-productive vines should be trimmed back in spring and early summer to prevent them from shading the developing flower buds and blocking the sunlight, thus reducing the number of flowers produced that season.
http://homeguides.sfgate.com/grapevin...