You use Obsidian and an Eye of Ender for making Ender Chests (and yes, it is confirmed that ender chest inventories will remain separate-- that is, each player will have his or her own inventories in his or her respective ender chests)
Currently, Emerald has no other purpose other than aesthetics and trading with Villagers.
And I think that there will be two different Golden Apples once 1.3 arrives. The original is coming back, but is given different abilities.
The current Golden Apple currently heals 4 hunger points and regenerates health for 5 seconds.
The new Golden Apple (original recipe, involving gold BLOCKS) will restore 4 hunger points and rapidly regenerate health for 30 seconds. It also provides Resistance and Fire Resistance for 5 minutes.
Both golden apples can be eaten with full hunger.