I read out your dream to my (well read) husband...he asked me to ask you if you have read any Ken Kerns? Sadly he died inside his earth house and my beloved said unless you are a soil engineer he thinks you are taking a big chance. I totally hear what you are saying about going to ground though! My dream is a hobbit house half way into a hill...well dreams are good! necessary to keep us going huh?
Best of luck, your place and your dream sounds wonderful to me! All the best from BC
Snowpeach