very interesting observations!
I represent the style of Master Nocquet (at least, I try to).
How we do the ikkyo pin? Hard to describe. After you got your partner down, extend the arm so you get an angle bigger than 90° between arm and spine (makes it more effective). Lengthen the arm (will provide some small space between the bones in uke's elbow) and take your arm next to your partner in tekatana position. Then bring it on the elbow and press down using your center. That's how I would describe it.
Ah, yes, I breathe differently. When I breath in while I bring the arm up it mostly results in me going (very little) backwards. So I breathe out during the whole technique (holds for irimi). Seems to work better for me......
Hope that helps.