Kristian - Follower of Christ. Well duh.

Breinholt - Don't know. Couldn't find any info.

Iversen - Basically means "Son of Iver". So, one of my ancestors was called Iver, from where the name originates.

As for Iver:
From the Old Norse name Ívarr, which was derived from the elements yr "yew, bow" and arr "warrior". During the Middle Ages it was brought to Britain by Scandinavian settlers and invaders, and it was adopted in Ireland, Scotland and Wales.