Boxing & unboxing is the process of converting a primitive value into an object oriented wrapper class (boxing), or converting a value from an object oriented wrapper class back to the primitive value (unboxing).
The Old Dalaran will stay in Northrend, so yes, mages are going to have 2 portals to dalaran (one to Northrend and one to the Broken Isles)
Rhonin, Dalaran and Legion. If Dalaran's going to be moving in Legion, is Rhonin still going to be yelling every time someone hands in that quest (whichever one it is)? If so, then WTB an addon, a /ignore or at least some earplugs to shut him up.