Is there any way to change your eye level when playing in First person perspective? If I increase the height of my character with the CK, the eye level remains the same. Increase the heights of other NPCs and suddenly you're looking at someone's chest rather than in the face. Is there a way to do it via the CK or another method or is not possible at all?

I think you need to change it in the .nif files. Something related is here:
http://jaredbangerter.hubpages.com/hub/How-to-Play-as-Monsters-In-Skyrim

but I think you'd better make a new race ro something or you'll break existing races. (I don't know how to do all that, I was barely able to follow the tutorial)

Thank you mate