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)
Ald'ruhn otherwise known as Old Run or Old Home in Dunmeris is large settlement in western Vvardenfell in the Ashlands region near Red Mountain. The city is also known as the Vvardenfell capital of the Great House Redoran.