eka sarva brahm, neha nanaasti kinchan
  —   einn er svinnur, enginn er annar.
one is ginnungagap, no other is

Enginn veit af hvers rótum renn
No man knows where from its roots come  –  askur Yggdrasils

mjötviður mær og ymur hið aldna tré
precious mjöt-viður (”measuring tree”), and (in the end, at ragnarök) moans the olden tree.

Who is/was Irmin, Irmino? Someone powerful?

Irminsul, to my mind, indicates transcendence. See it, for fun, my way.
Is irminsul vingameiður?

Good that they realized this not during the dark ages! They would have destroyed them all. Irminsul is found all over: Emblem of Firenze, the knot of the Christian Scouts –  oh boy !  And all the others.

Same Irminsul and Askur on Youteube