In what follows, I've assumed a concrete building with shear walls as the lateral system.
1) A vertical stiffness irregularity is unlikely. It would be more likely if it were a moment frame building with the main floor much taller than the floors above.
2) If there's a commonly encountered irregularity with this setup, I would guess that it would be a mass irregularity owing to the -- potentially -- much heavier mass of the transfer level. In my experience, this irregularity is more likely with transfer slabs than transfer beams.
That said, we know next to nothing about your building and it's conceivable that just about any of the NBCC irregularities might apply under the right set of circumstances.