You can't...
No. I tried it yesterday on the 360 and I duplicated my diamond picks!
To mine diamonds in Minecraft, you have to use an diamond or iron pick. Click and hold with your mouse on the diamond ore until it breaks. A block of diamond should come out of it and into your inventory. Then you have to cook it in your furnace to get diamonds.
To access a furnace in minecraft, simply click it!!!! Its that easy!!
No
Press E. It should leave the furnace GUI.
No, That was patched as of 1.73
To duplicate stuff in minecraft you have to be on multiplayer and two players must be in 1 chest with and item stack in it. They both have to click on it at the same time and it will beacome duplicated.
You automatically get 1
yes
Smelt Cobblestone in your furnace.
Burn cactus in a furnace.
dooplicator