Unfortunately, I cannot answer your question regarding the role the 3rd Armored Div. played in the occupation of Germany. When the fighting ended, I had been with the Division for over four years and had enough "points" for discharge. I left the unit in July, 1945.
You might try www.3ad.org , the website of the Association of 3rd AD Veterans, a group formed by those who served in the Division after WW II.