Not sure.
yes from what i have read it is like activating the kundalini
from what iv read, the yin chi is absorbed through the earth and the yang chi is absorved through the breath, the yang chi is supposed to be in the air. By focusing the breathing to the lower dantien, the lower dantien is able to fill with yang chi faster.
I think the kundailni method where they do the alternate nostril breathing is associated with positive and negative energy as a way to charge up the spine