* Your quest will complete for killing the Lich King when you defeat him on 10 man (I did not risk handing this in, as some people have reported that if you kill him in 25 man you do not get the chest).
* When the chest drops from LK 25, you loot the Lich King and the chest can be looted by you and only you (even with master looter on).
* The chest drops ONCE, upon handing in the chest you will not see the chest drop again, it is also probably worth noting that the rewards cannot be duplicated per Shadowmourne as the items are quest hand in rewards.
* Handing in the chest gives you a junkbox type item which upon opening gives you five items which start quests and RP events for each individual item, the Darion RP event is worth watching on youtube etc, however the rest are simply the character talking to you about their relationship with Arthas.
* All rewards are BOE, you are not forced to give any item to anybody; the only way someone can stop you from using the items is if you never kill the Lich King, apart from that; these items are the Shadowmourne wielder's unless he/she decides otherwise.