When you place the block in the world and activate (right click) it, you will be presented with a GUI similar to a chest's, but with six slots.
When you break the cooler it keeps its inventory, and while it is in your inventory and you are hungry, the cooler will feed you, first from it's buffer, then it's inventory.
If you look at the cooler's tooltip in your inventory, you may notice that it says whether its colored and/or transparent, and if you have food stored in it, it will even display the items in it and their quantities, as well as displaying the cooler's food buffer (keep in mind that 1 point in its buffer is one-half of a hunger icon).
Crafting:
Curse based modpacks and spotlights are welcomed, no need to ask.
