Found a video on Stuart Alve Olson.
He is a well known translator of many Taiji books.
http://www.youtube.com/watch?v=P0CWoTYs5NM
@ 5:05 He talks about Breath
http://youtu.be/P0CWoTYs5NM?t=5m5s
@ 6:49 Knee over toe
http://youtu.be/P0CWoTYs5NM?t=6m49s