1. Schematic: Jeeves http://db.pandawow.me?item=49050
2. To obtain that people with engineering need to loot 2 times some mobs, most often Library Guardians(http://www.db.pandawow.me?npc=29724/library-guardian). First time taking all items, then looting second time(Salvaging), for engineering parts, very similar to skinning. Second looting doesn't work here, we can loot only once even with engineering, making portable bank unobtainable.
3.Should be able to loot 2 times. Once normally, second time if we have engineering, and its mob that allows salvaging. Since that may need fixes on the looting system, and that may be messy, it can work if recipe is added at normal mob drop on that mob as well.
4. 23.April.2014(5 min ago).
5. x10
6. Depends how many people want engineering portable bank I guess.
Still, not game breaking so maybe 2-3?Though for people with engineering may be a lot higher.