There is a very detailed guide available for all the blocks, items and new mechanics added by this mod. Erasmus_Crowley suggest giving it a read to check out everything Erasmus_Crowley has added.
You can use this mod with any map and it will be both fun and useful, not just Skyblock. Still, Erasmus_Crowley recommend usingthe original Skyblock map by Noobcrew.
Zerokyuuni has released an expansion mod called Ex Aliquo which adds support for a fairly large and diverse collection of other mods. Make sure you check it out in his thread.
Download Ex Nihilo Mod 1.7.10