The portal leads to the other side, and the portal key is an object that opens the portal.
(This one has been playing Arcanum lately.)
About wands, and other items with Charges or Cast Once Per Day, those usually just fling off the spell without any considerable cast time.
For example; one of my character has a flute with the spell "Mindfog." In theory, the said character could be hiding, and appear "visible" at the very moment he flings off the spell.
Normally when you cast spells, it is one spell per round, and you fling off the spell roughly after the third second. Thus if you spot someone starting to cast a spell you may have enough time to use a wand or flute.
:D yup merchant of sorts sell anything or anyone....I mean He HELPS. :D atleast he did not show folks a portal shove them in and laugh at the fact he has the key and they do not.