The season pack gets you the first four dlcs for the price of the season pass, which is a reduced price. It looks like each dlc will ahve some character skins and weapon skins, but other than the liquid chrome skin, the season pass does not give you access
to any of the current weapon skins.
It is not available until November 1st, whether you have the season pass or no. If you have the season pass you still have to place Horde Pack dlc 1 in you queue the day it comes out for it to download.