Lenamare triggered it on teleportation spells, i.e. detecting them.
A portal is a gateway, like a runic gateway, saintly gateway etc.
So, I would think not as configured, however, he could probably adjust the triggers. The big question would be are all these portals/gates close enough in terms of energy signature–or whatever the trigger mechanism is to detect them and spring the trap.
I’m not a wizard, so have no clue.
As for skew space, it’s a twisting of the localverse that changes the flow of time. It’s not a different universe, it’s more like a warping of the localverse and is generally tied to a physical location/item etc.
As for the other questions…
[SPOILER]This will be coming up again in Book 4 and beyond in much more detail. :-k [/SPOILER]