The Primal Huntress can teach you to become a Wildwood Primalist. Unlike the other new ascendancy classes, the Primal Huntress lets you customise your tree using Charms that have randomly generated skills from the regular ascendancy classes. Charms are attribute-aligned magic items that can have up to two random modifiers on them.
Wildwood Primalists get access to other powerful abilities, such as a small extra backpack, or the ability to use warcries to cause corpses to drop extra items.
Primal Wisps can be used to purchase Charms from the Primal Huntress.
Yes:
(During the Path of Exile: Affliction Content Reveal it was mentioned that Vivid Wisps were associated with the Primal Huntress and Primal Wisps with the Warden of Eaves, however this has since changed to the above)